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PHYSIOLOGICAL ASPECTS OF SPERM TRANSPORT IN THE DOMESTIC PIG, SUS SCROFA. I. SEMEN DEPOSITION AND CELL TRANSPORT By R. Department
d
H.
F.
HUNTER
Agricultural Zoology, * School of Agriculture, University of Edinburgh
INTRODUCTION
Efficient transport of spermatozoa to the upper reaches of the Fallopian tubes of oestrous animals is an essential preliminary to fertilization. At the same time, it depends upon a co-ordinated series of physiological events that is particularly susceptible to malfunction or to interference by stress factors. It is no surprise, therefore, that studies on this topic have proliferated since the late nineteenth century, not only because of a fundamental interest in the transport and migration of gametes but, more recently, as an approach towards a potential means of alleviating infertility or of regulating fertility in man. Among the many reviews dealing with various aspects of sperm transport in the female reproductive tract, special mention should be made of treatments by Parkes (1960), Walton (1960), Bishop (1961), Austin (1964), Noyes (1968), Blandau (1969) and Bedford (1970). Perusal of the papers by Chang & Pincus (1951), Cross (1959), Noyes & Thibault (1962), Mann (1968), Noyes (1972) and Hafez (1973) will also prove valuable, whilst a concise review of sperm ascent to and distribution within the Fallopian tubes can be found in the recent paper of Thibault (1972). In all these studies, it is desirable to bear in mind a distinction between sperm transport, which implies a passive movement of cells in the genital tract, and sperm migration which clearly attributes great importance to the intrinsic motility of the cell. Although early investigators were inclined to view sperm ascent along the female tract as an outcome of the sperm cells' own movements (Mann, Polge & Rowson, 1956), it is now generally accepted that the role of sperm motility becomes paramount only in certain regions of the tract (e.g. cervix and utero-tubal junction) and during penetration of the egg membranes. The rapidity with which spermatozoa appear in the upper portions of the Fallopian tubes after mating or artificial insemination has emphasized that sperm motility alone could not have contributed significantly to passage over the relatively large distances involved. The journey is probably effected at all
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West Mains Road, Edinburgh EH9 3JG, Scotland. 3
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stages by contractile mechanisms in the musculature of the tract, part of the transportation process undoubtedly being assisted by central nervous mechanisms set in motion by the sexual stimulation attending coitus (Van Demark, 1958; Cross, 1959). Nonetheless, when the duration of oestrus is long and mating takes place early, active migration of spermatozoa from storage regions such as the lower isthmus must be of physiological significance, especially since the enhanced muscular contractions of the uterus and tubes promoted by oxytocin released at coitus would long since have ceased. As a corollary, it may be inferred that rapid post-coital transport of spermatozoa to the ampulla in this latter situation would have had little influence on fertility. Two further points of significance should be mentioned at this stage. First, in comparison with the number of spermatozoa deposited in the female tract at mating, there is a massive reduction in sperm numbers as one proceeds towards the ampulla of the Fallopian tube. This has been reasoned to reduce the chances of polyspermy by restricting the numbers of spermatozoa that achieve the site offertilization (Braden, Austin & David, 1954.). Second, during this marked diminution in sperm numbers, the cells are progressively removed from the seminal plasma, and their economy becomes strongly influenced by the luminal fluids of the uterus and Fallopian tubes. This situation appears to have a direct bearing on the metabolic activity of ejaculated spermatozoa, and may also be associated with development of the capacitated state. Before proceeding to a more detailed discussion of sperm transport, it would seem important to consider briefly the evolutionary or biological significance of intra-uterine deposition of the ejaculate. It is possible to view this site of ejaculation as an adaptation to accommodate the copious production of seminal fluid by the male. More plausible, however, would be the argument that the intra-uterine deposition of semen in large volumes is a feature that should contribute to successful passage of spermatozoa to the site offertilization. If this interpretation is correct, then for reasons not readily apparent, cervical and uterine transit may have proved a formidable undertaking for spermatozoa in ancestral forms of the domestic pig. The regulatory and storage roles enjoyed by the cervix in vaginal depositors such as the rabbit, ruminants and primates appear to have been taken over in large measure in the pig by the utero-tubal junction and lower regions of the Fallopian tube. These remarks notwithstanding, species differences in the survival time of spermatozoa do not appear to be correlated with the site of deposition of semen at coitus, or with its mode of transport in the female tract (Parkes, 1960). MATING AND EJACULATION
Copulation by the boar is a protracted affair, ejaculation being promoted by pressure on the distal portion of the penis, whereas in the ram and bull, by contrast, coitus is rapid and the stimulus for ejaculation is more sensitive to temperature (Walton, 1960). The taut and oedematous condition of the cervix in oestrous pigs (Burger, 1952; Smith & Nalbandov, 1958; Melrose & O'Hagan, 1961; Rigby, 1967) provides the appropriate stimulus for ejaculation, the spiral
SPERM TRANSPORT IN THE PIG
tip of the penis engaging the strongly-ribbed, muscular folds of this portion of the female tract (Rodolfo, 1934b; Melrose, 1963). During coitus, which may last for 4·5 to 10 minutes (McKenzie, Miller & Bauguess, 1938; Burger, 1952), semen is propelled by muscular contractions of the male tract almost directly into the pars indivisa of the bicornuate uterus (Rodolfo, 1934b; Burger, 1952; Du Mesnil du Buisson & Dauzier, 1955a; Polge, 1956), although passing contact may be made with the proximal region of the cervical canal. The considerable volume of the ejaculate, frequently amounting to nearly half a litre, has been the subject of comment since the publications of Rodolfo (1934b), McKenzie et at. (1938), Wallace (1949), Burger (1952) and Glover (1955). However, the physiological basis for the production of such a large volume of fluid by the accessory glands appears not to have received detailed consideration, although the fate of the seminal plasma deposited in the female tract has been discussed in various papers (see below). NATURE OF SEMEN AND DENSITY OF SPERMATOZOA
The semen of boars is known to be ejaculated in fairly distinct fractions (Rodolfo, 1934b; McKenzie et at., 1938; Ito et at., 1948; Wallace, 1949), commencing with both watery and gel pre-sperm secretions, followed by sperm-rich and post-sperm fractions (McKenzie et at., 1938; Glover, 1955; Polge, 1956) which, together with the gelatinous portion (Rodolfo, I 934b), may then be repeated in the same sequence in a second wave. It is uncertain whether fluctuation in sperm density during the prolonged ejaculation has significance in the context of sperm transport to the Fallopian tubes, but McKenzie et at. (1938) and Du Mesnil du Buisson & Dauzier (1955a) have suggested that this sequence may assist progress of the sperm-rich fraction through the uterine horns. On the other hand, it is known that shortly after or even during emission of a "normal" volume of semen, the ovarian end of the uterine horns and the utero-tubal junction may be bathed by semen containing the full density of spermatozoa in the ejaculate, or indeed a significantly higher concentration of cells than at the caudal region of the horns (Du Mesnil du Buisson & Dauzier, 1955a). Although the enhanced contractile activity of the oedematous uterus displayed during oestrus (Corner, 1923; Keye, 1923) may facilitate distribution of the ejaculate throughout the horns, the sheer volume of the semen will cause some distension of the uterus in many animals, together with passage of semen to the utero-tubal junction. This engorged state of the uterus can frequently be seen when laparotomy is performed within an hour or so of mating (Mann, Polge & Rowson, 1956), or at post-mortem examination within a similar interval of time (Burger, 1952; Du Mesnil du Buisson & Dauzier, 1955a). Accordingly, following natural mating with a mature boar, problems of sperm transport may not arise in the lower regions of the female tract; this is, of course, in contrast to the situation after artificial insemination with a reduced volume of semen, which may itself have been diluted. Details of sperm concentration and the total content of spermatozoa in the ejaculate have been published by many authors (Lewis, 191 I; Rodolfo, 1934a;
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McKenzie et at., 1938; Wallace, 1949), from which it is clear that the total number of spermatozoa produced by the boar in a single ejaculate is remarkably high; the average value for a number of boars given by Rodolfo (I 934a) was 7.83 X 10 10 cells, but a considerable range is found. The concentration of spermatozoa may vary between o· I to lO X 10 8 cells per ml, with a mean of about I to 2 X 10 8 cells per ml (Polge, 1956). There appears to be no correlation between the volume of semen and the total number of spermatozoa (Rodolfo, 1934a), or between semen volume and sperm density (McKenzie et at., 1938; Glover, 1955). TIMING OF SPERM TRANSPORT
In the light of the above remarks concerning passage of semen to the utero-tubal junction, it is not surprising that spermatozoa have been recorded in the Fallopian tubes very shortly after mating. Nonetheless, some disagreement is apparent in the early reports on the rate of sperm transport. For example, Rodolfo (1934b) noted spermatozoa in the Fallopian tubes of a sow within 40 min of artificial insemination, whereas McKenzie et at. (1935) were unable to find spermatozoa in the mid-region of the tubes of sows until 5 h after mating. More recent investigations, however, have demonstrated on the basis of post-mortem examination that boar spermatozoa can reach the upper half of the tubes within 15 min (Burger, 1952) or 30 min (Ito, Kudo & Niwa, 1959; First et at., 1968a) of mating or artificial insemination. Likewise, Mann et at. (1956) recovered spermatozoa from the Fallopian tubes of a gilt by flushing these at laparotomy 40 min after mating. There is general agreement that spermatozoa can reach the upper half of the tubes within two hours of mating (Du Mesnil du Buisson & Dauzier, 1955b; Pitkjanen, 1960, 1962; Pitkjanen & Subin, 1961). As pointed out by Baker, Dziuk & Norton (1968), emphasis has too frequently been placed on the minimum time required for spermatozoa to reach the site of fertilization, as in those species in which mating precedes ovulation by a number of hours, rapid transport of spermatozoa to the ampulla may not be essential. A more meaningful assessment of the rate of sperm transport might be derived from measuring the interval between post-ovulatory deposition of semen in the female tract and sperm penetration of the eggs, despite the fact that this would refer only to live spermatozoa. In experiments in which the time of ovulation was controlled precisely by means of an injection of human chorionic gonadotrophin given during pro-oestrus (Dziuk, Polge & Rowson, 1964; Hunter, 1967a, b), spermatozoa were found in the zona pellucida of the egg within 2 h of intra-cervical insemination (Hunter & Dziuk, 1968). That considerable numbers of spermatozoa can be attached to the zona pellucida within 3 h of mating at the time of ovulation has been shown in subsequent studies (Hunter, 1972; Hunter & Hall, 1973, 1974a). In an attempt to define further the timing of entry of a population of spermatozoa into the Fallopian tubes, a technique of post-coital isolation of the tubes was employed (Hunter & Hall, 1974b). Animals were mated shortly after the
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time of induced ovulation, and the Fallopian tubes were separated under general anaesthesia from the uterine horns some 30, 45 or 60 min after mating. Penetrated eggs were found in all three groups within three hours of surgery, indicating that sufficient spermatozoa to fertilize a proportion of the eggs had entered the Fallopian tubes within 30 min of mating. By employing surgical deposition of whole semen directly into the uterus, it was also shown in this study that separation of the tubes from the uterus within 15 min of insemination permitted penetration of some eggs during the ensuing 3 h (Hunter & Hall, 1974h). This finding therefore supports the concept ofa rapid entry of sperm atozoa into the Fallopian tubes of oestrous pigs, and may also endorse the view that the rate of sperm ascent to the site of fertilization is accelerated around the time of ovulation (Du Mesnil du Buisson & Dauzier, 1955h; Ito et at., 1959) or towards the end of oestrus (Pitkjanen, 1960), possibly due to heightened activity in the muscular compartments of the tract. The latter situation would clearly have physiological advantages in reducing the risk of penetration of ageing eggs. NUMBERS OF SPERMATOZOA TRANSPORTED
Details of the numbers of spermatozoa recorded in the Fallopian tubes of sows and gilts have been given by various authors (Du Mesnil du Buisson & Dauzier, 1955a, b; Rigby, 1966; Baker & Degen, 1972); their results indicate that only a very small proportion of the massive number of spermatozoa deposited at mating or artificial insemination can be recovered from this region of the tract. The population of spermatozoa in the tubes may initially undergo considerable quantitative change, since Rigby (1964, 1966) has reported that sperm numbers increase until 12 h after insemination, and Pitkjanen (1960) noted an increase until 24 to 30 h after mating. But these findings contrast strongly with the study of First et at. (I 968b), in which the sperm population in the Fallopian tubes remained unchanged from i- to 24 h after insemination. If a sufficient volume of semen is inseminated so that fluid reaches the utero-tubal junction, the number of spermatozoa entering the tubes has been shown to be directly related to the concentration of spermatozoa in the inseminate (Rigby, 1964; Baker et at., 1968). This relationship has been interpreted as representing passage of an aliquot of semen to the site of fertilization (Baker et at., 1968). Thus the concentration of spermatozoa at the site of fertilization is likely to be related to the number of spermatozoa persisting at the utero-tubal junction (Rigby, 1964, 1966). Returning to our own approach of estimating quantitative aspects of sperm transport by noting the number of spermatozoa associated with the eggs, a brief summary has recently been given (Hunter, 1974). The mean number of spermatozoa around the small proportion of eggs with some sperm recovered two hours after insemination was 5'0 (range I to 14), increasing to 9'3 (range I to 80) at three hours after insemination (see Hunter & Dziuk, 1968). In a later study, the mean number of spermatozoa associated with the zona pellucida
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increased from 6·8 (range I to 25) at 3 h to 109'2 (range I to 466) some 6 h after mating at the time of ovulation (Hunter, 1972). By the time the two-celled stage is reached, two hundred or more spermatozoa may have penetrated the zona (Thibault, 1959; Hancock, 1961; Hancock & Hovell, 1961, 1962), and this number can increase substantially during the tubal descent of the embryo. These figures indicate that under conditions of mating or insemination close to the time of ovulation, a progressive increase in sperm numbers associated with the egg is occurring during the interval from activation of the secondary oocyte until passage of the developing embryo into the uterus. At the latter stage, the number of spermatozoa in the zona may be of the order of several hundred, and on occasions exceed four to five hundred (Hunter & Leglise, 1971). This significant increase in zona sperm could be invoked as evidence against the phagocytosis of spermatozoa in the Fallopian tubes during the 46 to 48 h that the embryos are in transit (see below). TRANSPORT OF LIVE VS. DEAD SPERMATOZOA
First et at. (I 968b) and Baker & Degen (1972) have reported that dead spermatozoa are transported through the utero-tubal junction into the isthmus. However, the former authors also claim that dead spermatozoa enter the Fallopian tube at the same "rate" as live spermatozoa. This claim stands in marked contrast to the work of Baker & Degen, in which consistently fewer dead spermatozoa were recovered from the upper uterine horns and tubes when gilts were inseminated with equal numbers of both. This latter study needs to be interpreted with caution, since it was conducted on hormone-treated prepuberal gilts inseminated whilst reclining on their backs under general anaesthesia, with sperm-collecting cannulae ligated into the reproductive tract. Nonetheless, Baker & Degen (1972) did remark that the mechanism whereby dead spermatozoa are transported through the utero-tubal junction is not well understood, although they suggested that fluid containing both live and dead spermatozoa is forced through the junction by uterine contractions. Such a mode of passage is unlikely to occur during oestrus, since pressure from the uterine side at this stage of the cycle would effectively close the junction (Andersen, 1928; Lee, 1928). Indeed, the uterine wall may rupture before fluid can be squeezed manually through the junction into the tube. These observations on the transport and persistence of dead spermatozoa in the female tract may be contrasted with the transport and survival of frozenthawed spermatozoa in gilts (PoIge, Salamon & Wilmut, 1970; Wilmut & Polge, 1971). In the latter situation, it has been noted that frozen-thawed boar spermatozoa rarely fertilize eggs when inseminated via the cervix, although high fertility has been obtained following surgical insemination directly into the tubes (Polge et at., 1970). Taking this finding, together with the fact that very few spermatozoa are recovered from the tubes after intra-cervical insemination of frozen-thawed material, it might be inferred that a degree of selection is occurring in the uterus or at the utero-tubal junction against such treated sperm a tozoa.
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ACKNOWLEDGEMENTS
Unpublished experiments reported in this paper were supported by a grant from the Agricultural Research Council, for which grateful acknowledgement is made. I am also indebted to a number of colleagues in Edinburgh for kindly commenting on portions of the manuscript. REFERENCES
ANDERSEN, D. E. (1928). Am. J. Anat. 42, 255. AUSTIN, C. R . (1964). Proc. 5th Int. Congr. Anim. Reprod. 3, 7. BAKER, R. D. & DEGEN, A. A. (1972). J . Reprod. Fert. 28, 369. BAKER, R. D., DZIUK, P.]. & NORTON, H. W . (1968). J. Anim. Sci. 27,88. BEDFORD,]. M. (1970). Proc. qj21st Mosbach Symposium , Berlin: Springer-Verlag. BISHOP, D . W. (1961). In Sex and Internal Secretions, Ch. 13, 3rd edn. ed. W. C. Young, Baltimor e: Williams & Wilkins. BLANDAU, R.]. (1969). In The Mammalian Oviduct, Ch. 5, ed. E. S. E. Hafez & R . ]. Blandau. University of Chicago Press. BRADEN, A. W. H ., AUSTIN, C. R. & DAVID, H. A. (1954). Aust. J . bioi. Sci. 7,391. BURGER,]. F. (1952). Onderstepoort J . vet. Res. Suppl. NO.2. CHANG, M. C. & PINCUS, G. (1951 ). Phy siol. R ev. 31, I. CORNER, G. W. (1923). Am. J. Anat. 32, 345. CROSS, B. A. (1959). In Recent Progress in the Endocrinology qj R eproduction, ed. C. W. Lloyd. New York: Academic Press. Du MESNIL DU BUISSON, F. & DAUZIER, L. (I955a ). Annis. Endocr. 16,413. Du MESNIL DU BUISSON, F . & DAUZIER, L . (I955b). C.R. Soc. B ioI. 149,76. DZIUK, P. ]., POLGE, C . & ROWSON, L. E. (1964). J . Anim. Sci. 23, 37. FIRST, N. L., SHORT, R . E. , PETERS,]. B. & STRATMAN, F. W . (1968a). J. Anim. Sci. 27, 1032. FIRST, N. L., SHORT, R. E ., PETERS, ]. B. & STRATMAN, F. W. (1968b). J. Anim. Sci. 27, 1037. GLOVER, T . D. (1 955). Vet. Rec. 67, 36. HAFEZ, E. S. E. (1973). Am. J. Obstet. Gynec. 115,7°3. HANCOCK,]. L. (I961).J. Reprod. Fert. 2, 307. HANCOCK,]. L. & HOVELL, G.]. R. (1961). Anim. Prod. 3,153. HANCOCK,j. L. & HOVELL, G.]. R. (1962). Anim. Prod. 4, 91. HUNTER, R. H. F. (1967a). Vet. Rec. 81, 21. HUNTER, R. H . F. (1967b). J. Reprod. Fert. 13, 133. HUNTER, R. H. F. (1972). J. Reprod. Fert. 29,395. HUNTER, R. H. F. (1974). Anat. Rec. 178, 169. HUNTER, R. H. F. & DZIUK, P . ] . (1968). J. Reprod. Fert. 15, 199. HUNTER, R. H. F. & HALL, j. P. (1973). J. R eprod. Fert. 35, 593. HUNTER, R . H. F. & HALL, ]. P. (1974a). J. expo Zool. 188,203. HUNTER, R. H. F. & HALL,]. P. (1974b). Anat. Rec. 180,597. HUNTER, R. H. F. & LEGLISE, P. C. (1971). J. Reprod. Fert. 24, 233 . ITo, S., K UDO, A. & NIWA, T. (1959) . Annis. Zootech., Ser. D , Suppl. p. 105. ITo, S., NIWA, T., KUDO, A. & MIZUHO, A. (1948). Zootech. Exp. Sta., Chiba, Res. Bull. 55,54. KEYE, j . D . (1923). Bull. Johns Hopkins Hosp. 34, 60. LEE, F. C. (1928). Bull. Johns Hopkins Hosp. 42, 335. LEWIS, L. L. (191 I). Okla. Agric. Exp. Sta. Bull., No. 96. McKENZIE, F. F., MILLER, ]. C. & BAUGUESS, L. C. (1938). Res. Bull. Mo. Agric. Exp. Sta. No. 279. McKENZIE, F. F., TERRILL, C. E., WARBRITTON, V. & NAHM, L . ]. (1935). Res. Bull. Mo. Agric. Exp. Sta. No. 358, 20. MANN, T . (1968). Proc. 6th Int. Congr. Anim. Reprod. 1,3. MANN, T., POLGE, C. & ROWSON, L. E. A. (1956). J. Endocr. 13, 133. MELROSE, D. R. (1963). Brit. vet. J. I19, 532. MELROSE, D. R. & O'HAGAN, C. (1961). Proc. 4th Int. Congr. Anim. R eprod. 4,855. NoYES, R. W. (1968). In Progress in Infertility. ed. S.]. Behrman & R . W. Kistner. Boston: Little, Brown. NOYES, R . W. (1972). Pathophysiolog}' of Gestation D isorders, 1,63.
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NoYES, R. W. & THIBAULT, C. (1962). Fert. SteriZ. 13,346. PARKES, A. S. (1960). In Marshall's Physiology of Reproduction, Chap. 9, vol. I, ed. A. S. Park('s. London: Longmans. PITKJANEN, I. G. (1960). Z. Obsc. Bioi. 21,28. PITKJANEN, I. G. (1962) . Vet. Med. 7,487. (Anim. Breed. Abstr. 30, 2699). PITKJANEN, I. G. & SUBIN, A. A. (1961). Svinovodstvo, 15,37. POLGE, C. (1956). Vet. Rec. 68,62. POLGE, C., SALAMON, S. & W1LMUT, I. (1970). Vet. Rec. 87, 424. RIGBY,j. P. (1964). Proc. 5th Int. Gongr. Anim. Prod. 4, 421. RIGBY,j. P. (1966).J. Reprod.Fert. II, 153. RIGBY, j. P. (1967). Vet. Rec. 80, 672. RODOLFO, A. (193¥). Philipp. J. Sci. 53, 183. RODOLFO, A. (1934b). Philipp. J. Sci. 55,13. SMITH, J. C. & NALBANDOV, A. V. (1958). Am. J. Vet. Res. 19, 15· THIBAULT, C. (1959). Annis. Zootech., Ser. D, Suppl. p. 165. THIBAULT, C. (1972). Int. J. Fert. 17, I. VAN DEMARK, N. L. (1958). Int. J. Fertil. 3, 220. WALLACE, C. (1949) . J. Endocrin. 6, 205. WALTON, A. (1960). In Marshal/'s Physiology of Reproduction. Ch. 8, vol. I, ed. A. S. Parkes. London: Longmans. WILMUT, I. & POLGE, C. (1971). J. Reprod. Fert. 25, 301. (Accepted for publication
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October 1974)
Aspects physiologique du transport du sperllle chez Ie porc dOlllestique, Sus scrofa I. DepOt du spenne et transport cellulaire (Hunter) ResUllle. Le processus de transport spermatique, migration et stockage ont ete examines pour Ie pore domestique chez lequel on pense que Ie volume d'ejaculation penetre dans I'uterus pendant Ie cOlt. Apres s'etre concentre sur la signification evolutive possible du site d'insemination, on porta son attention a la periode etendue de I'oestrus, a I'important volume du sperme depose, et au fait que la jonction utero-tubaire puisse etre baignee par Ie sperme avant que I'accouplement ne soit termine. La signification des trois "fractions" du sperme en relation avec la concentration et Ie passage des spermatozoldes a ete consideree, comme I'a ete I'importance de la jonction utero-tubaire et I'isthme de la trompe de Fallope dans la regulation du transport spermatique. Le degre de selection au niveau de la jonction utero-tubaire entre spermatozoldes vivants et morts, et entre les populations de cellules homologues et heterologues, a encore besoin d'eclaircissement. On a note des regions specialisees dans Ie stockage du sperme dans Ie tractus reproducteur feminin, tels que les diverticules de la jonction utero-tubaire et entre les plis de I'isthme caudal. De differents modes de repartition du sperme dans Ie tractus feminin ont ete decrits, mais l'implication des leucocytes polynucleaires dans la mobilisation des spermatozoldes a partir des trompes de Fallope est discutable. Com me pour Ie devenir du plasma seminal, ceci a ete poursuivi chimiquement, mais les determinations physiologiques a partir des etudes sur la capacite sont aussi considerees com me etant de valeur. En definitive, Ie fait est accentue de par les mesures temporelles et quantitatives du transport spermatique sont seulement biologiquement significatives lorsqu'elles sont considerees par rapport au reglage de l'ovulation et a la fecondation. Physiologische Aspekte der Sperlllawanderung bem dOlllestizierten Sus scrofa. I. Deponierung von Selllen und Zellenfortbewegung (Hunter) Zusall1ll1enfassung. Die Vorgange der Deponierung des Spermas, dessen Wanderung und seine Bewahrung beim Hausschwein sind untersucht worden. Man nimmt an, dass beim Koitus das gesamte Ejakulat in den Uterus gelangt. Nach Konzentration auf die mogliche evolutionare Signifikanz einer solchen Inseminationslokalisation wir auf die verlangerte Oestruszeit, auf die grosse Menge des deponierten Spermas und auf das Faktum hingewiesen, dass die utera-tubale Verbindung sich in einem Spermabad befinde, beY~r the Koitus beendet
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sei. Die Signifikanz der drei "Fraktionen" im Sperma wurde in Betracht gezogen in Beziehung zur Konzentration und Passage der Spermazozoen; und desgleichen die Wichtigkeit der utero-tubalen Kommunikation und des Isthmus der Tube und ihre Bedeutung filr die Regulierung der Spermawanderung. Geklart muss noch werden, bis zu welchem Grade an der utero-tubalen Verbindungsstelle eine Aussonderung zwischen lebenden und toten Spermien und zwischen homologen und h eterologen Zellen stattfindet. Man fand spezialisierte Zonen, in denen Sperma in den weiblichen R eproduktionsorganen aufbewahrt wird z.B. die Diverticula der utero-tubalen Verbindungsstelle und in den Falten des caudal en Isthmus. Verschiedene Modalitaten der Disposition von Sperma vom weilblichen Genitaltrakt sind beschrieben worden, aber es ist fraglich, ob polymorph nuklare Leukozyten am Transport d er Spermien aus den Tuben beteiligt sind. Urn zu untersuchen, was aus d em Plasma im Semen wird, sind chemische Untersuchungen un tern ommen worden, doch dilrften physiologische Beurteilungen auf Grund von Untersuchungen der Capacitation ebenfalls wertvoll sein. Schliesslich wird betont, dass temporale und quantitative M essung der Spermabewegung nur dann von biologischer Bedeutung sind, wenn sie in Beziehung zur Zeit des Auftretens von Ovulation und Befruchtung betrachtet werden. Aspectos fisiologicos del transporte de esperlWl en el cerdo dOlllestico Sus sero/a. I. Deposicion del selllen y transporte de celulas (Hunter) ResulIlen. Se h an revisado los procesos del transporte, migracion y almacenaje de esp erma en el cerdo domestico, del cual se cree que la mayor parte del ejaculado entra eI utero durante eI coito. Tras concentrarla en eI posible significado evolutivo de este pun to d e inseminacion, se llama atencion al extenso periodo del oestro, a la gran cantidad del semen depositado y al hecho de que la juntura uterotubaria puede ser bafiada por eI semen antes de que se termine eI apareamiento. Se ha considerado eI significado de las tres "fracciones" en semen en relacion ala concentracion y paso de espermatozoos, asi como la importancia de lajuntura uterotubaria y eI istmo de la trompa d e Falopio en la regulacion del transporte de la esperma. El grado de seleccion en la juntura uterotubaria entre los esp ermatozoos vivos y muertos, y entre poblaciones de celulas homologas y h eterologas, necesita ser aclarado. Se han abservado regiones especializadas para eI almacenaje de la esperma en eI aparato reproductor de la hem bra, tales como las diverticulas de la juntura uterotubaria y entre los pliegues del istmo caudal. Se han descrito varios me todos de expulsion de la esperma del aparato femenino, pero la asistencia de leucocitos polimorfonucleares en la expulsion de expermatozoos de la tromp a d e Falopio es dudosa. En cuanto al destino del plasma seminal, se ha seguido desde eI pun to de vista quimico, p ero las evaluaciones fisiologicas de estudios sobre la capacitacion han probado ser tambien valiosas. Finalmente, se subraya eI hecho de que tanto las m edidas temporarias como cuantitativas del transporte d e la esperma solamente tienen significado biologico cuando se consideran en relacion al momenta exacto de ovulacion y fertilizacion.
PHYSIOLOGICAL ASPECTS OF SPERM TRANSPORT IN THE DOMESTIC PIG, SUS SCROFA. I. SEMEN DEPOSITION AND CELL TRANSPORT By R. Department
d
H.
F.
HUNTER
Agricultural Zoology, * School of Agriculture, University of Edinburgh
INTRODUCTION
Efficient transport of spermatozoa to the upper reaches of the Fallopian tubes of oestrous animals is an essential preliminary to fertilization. At the same time, it depends upon a co-ordinated series of physiological events that is particularly susceptible to malfunction or to interference by stress factors. It is no surprise, therefore, that studies on this topic have proliferated since the late nineteenth century, not only because of a fundamental interest in the transport and migration of gametes but, more recently, as an approach towards a potential means of alleviating infertility or of regulating fertility in man. Among the many reviews dealing with various aspects of sperm transport in the female reproductive tract, special mention should be made of treatments by Parkes (1960), Walton (1960), Bishop (1961), Austin (1964), Noyes (1968), Blandau (1969) and Bedford (1970). Perusal of the papers by Chang & Pincus (1951), Cross (1959), Noyes & Thibault (1962), Mann (1968), Noyes (1972) and Hafez (1973) will also prove valuable, whilst a concise review of sperm ascent to and distribution within the Fallopian tubes can be found in the recent paper of Thibault (1972). In all these studies, it is desirable to bear in mind a distinction between sperm transport, which implies a passive movement of cells in the genital tract, and sperm migration which clearly attributes great importance to the intrinsic motility of the cell. Although early investigators were inclined to view sperm ascent along the female tract as an outcome of the sperm cells' own movements (Mann, Polge & Rowson, 1956), it is now generally accepted that the role of sperm motility becomes paramount only in certain regions of the tract (e.g. cervix and utero-tubal junction) and during penetration of the egg membranes. The rapidity with which spermatozoa appear in the upper portions of the Fallopian tubes after mating or artificial insemination has emphasized that sperm motility alone could not have contributed significantly to passage over the relatively large distances involved. The journey is probably effected at all
* Postal address:
West Mains Road, Edinburgh EH9 3JG, Scotland. 3
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stages by contractile mechanisms in the musculature of the tract, part of the transportation process undoubtedly being assisted by central nervous mechanisms set in motion by the sexual stimulation attending coitus (Van Demark, 1958; Cross, 1959). Nonetheless, when the duration of oestrus is long and mating takes place early, active migration of spermatozoa from storage regions such as the lower isthmus must be of physiological significance, especially since the enhanced muscular contractions of the uterus and tubes promoted by oxytocin released at coitus would long since have ceased. As a corollary, it may be inferred that rapid post-coital transport of spermatozoa to the ampulla in this latter situation would have had little influence on fertility. Two further points of significance should be mentioned at this stage. First, in comparison with the number of spermatozoa deposited in the female tract at mating, there is a massive reduction in sperm numbers as one proceeds towards the ampulla of the Fallopian tube. This has been reasoned to reduce the chances of polyspermy by restricting the numbers of spermatozoa that achieve the site offertilization (Braden, Austin & David, 1954.). Second, during this marked diminution in sperm numbers, the cells are progressively removed from the seminal plasma, and their economy becomes strongly influenced by the luminal fluids of the uterus and Fallopian tubes. This situation appears to have a direct bearing on the metabolic activity of ejaculated spermatozoa, and may also be associated with development of the capacitated state. Before proceeding to a more detailed discussion of sperm transport, it would seem important to consider briefly the evolutionary or biological significance of intra-uterine deposition of the ejaculate. It is possible to view this site of ejaculation as an adaptation to accommodate the copious production of seminal fluid by the male. More plausible, however, would be the argument that the intra-uterine deposition of semen in large volumes is a feature that should contribute to successful passage of spermatozoa to the site offertilization. If this interpretation is correct, then for reasons not readily apparent, cervical and uterine transit may have proved a formidable undertaking for spermatozoa in ancestral forms of the domestic pig. The regulatory and storage roles enjoyed by the cervix in vaginal depositors such as the rabbit, ruminants and primates appear to have been taken over in large measure in the pig by the utero-tubal junction and lower regions of the Fallopian tube. These remarks notwithstanding, species differences in the survival time of spermatozoa do not appear to be correlated with the site of deposition of semen at coitus, or with its mode of transport in the female tract (Parkes, 1960). MATING AND EJACULATION
Copulation by the boar is a protracted affair, ejaculation being promoted by pressure on the distal portion of the penis, whereas in the ram and bull, by contrast, coitus is rapid and the stimulus for ejaculation is more sensitive to temperature (Walton, 1960). The taut and oedematous condition of the cervix in oestrous pigs (Burger, 1952; Smith & Nalbandov, 1958; Melrose & O'Hagan, 1961; Rigby, 1967) provides the appropriate stimulus for ejaculation, the spiral
SPERM TRANSPORT IN THE PIG
tip of the penis engaging the strongly-ribbed, muscular folds of this portion of the female tract (Rodolfo, 1934b; Melrose, 1963). During coitus, which may last for 4·5 to 10 minutes (McKenzie, Miller & Bauguess, 1938; Burger, 1952), semen is propelled by muscular contractions of the male tract almost directly into the pars indivisa of the bicornuate uterus (Rodolfo, 1934b; Burger, 1952; Du Mesnil du Buisson & Dauzier, 1955a; Polge, 1956), although passing contact may be made with the proximal region of the cervical canal. The considerable volume of the ejaculate, frequently amounting to nearly half a litre, has been the subject of comment since the publications of Rodolfo (1934b), McKenzie et at. (1938), Wallace (1949), Burger (1952) and Glover (1955). However, the physiological basis for the production of such a large volume of fluid by the accessory glands appears not to have received detailed consideration, although the fate of the seminal plasma deposited in the female tract has been discussed in various papers (see below). NATURE OF SEMEN AND DENSITY OF SPERMATOZOA
The semen of boars is known to be ejaculated in fairly distinct fractions (Rodolfo, 1934b; McKenzie et at., 1938; Ito et at., 1948; Wallace, 1949), commencing with both watery and gel pre-sperm secretions, followed by sperm-rich and post-sperm fractions (McKenzie et at., 1938; Glover, 1955; Polge, 1956) which, together with the gelatinous portion (Rodolfo, I 934b), may then be repeated in the same sequence in a second wave. It is uncertain whether fluctuation in sperm density during the prolonged ejaculation has significance in the context of sperm transport to the Fallopian tubes, but McKenzie et at. (1938) and Du Mesnil du Buisson & Dauzier (1955a) have suggested that this sequence may assist progress of the sperm-rich fraction through the uterine horns. On the other hand, it is known that shortly after or even during emission of a "normal" volume of semen, the ovarian end of the uterine horns and the utero-tubal junction may be bathed by semen containing the full density of spermatozoa in the ejaculate, or indeed a significantly higher concentration of cells than at the caudal region of the horns (Du Mesnil du Buisson & Dauzier, 1955a). Although the enhanced contractile activity of the oedematous uterus displayed during oestrus (Corner, 1923; Keye, 1923) may facilitate distribution of the ejaculate throughout the horns, the sheer volume of the semen will cause some distension of the uterus in many animals, together with passage of semen to the utero-tubal junction. This engorged state of the uterus can frequently be seen when laparotomy is performed within an hour or so of mating (Mann, Polge & Rowson, 1956), or at post-mortem examination within a similar interval of time (Burger, 1952; Du Mesnil du Buisson & Dauzier, 1955a). Accordingly, following natural mating with a mature boar, problems of sperm transport may not arise in the lower regions of the female tract; this is, of course, in contrast to the situation after artificial insemination with a reduced volume of semen, which may itself have been diluted. Details of sperm concentration and the total content of spermatozoa in the ejaculate have been published by many authors (Lewis, 191 I; Rodolfo, 1934a;
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McKenzie et at., 1938; Wallace, 1949), from which it is clear that the total number of spermatozoa produced by the boar in a single ejaculate is remarkably high; the average value for a number of boars given by Rodolfo (I 934a) was 7.83 X 10 10 cells, but a considerable range is found. The concentration of spermatozoa may vary between o· I to lO X 10 8 cells per ml, with a mean of about I to 2 X 10 8 cells per ml (Polge, 1956). There appears to be no correlation between the volume of semen and the total number of spermatozoa (Rodolfo, 1934a), or between semen volume and sperm density (McKenzie et at., 1938; Glover, 1955). TIMING OF SPERM TRANSPORT
In the light of the above remarks concerning passage of semen to the utero-tubal junction, it is not surprising that spermatozoa have been recorded in the Fallopian tubes very shortly after mating. Nonetheless, some disagreement is apparent in the early reports on the rate of sperm transport. For example, Rodolfo (1934b) noted spermatozoa in the Fallopian tubes of a sow within 40 min of artificial insemination, whereas McKenzie et at. (1935) were unable to find spermatozoa in the mid-region of the tubes of sows until 5 h after mating. More recent investigations, however, have demonstrated on the basis of post-mortem examination that boar spermatozoa can reach the upper half of the tubes within 15 min (Burger, 1952) or 30 min (Ito, Kudo & Niwa, 1959; First et at., 1968a) of mating or artificial insemination. Likewise, Mann et at. (1956) recovered spermatozoa from the Fallopian tubes of a gilt by flushing these at laparotomy 40 min after mating. There is general agreement that spermatozoa can reach the upper half of the tubes within two hours of mating (Du Mesnil du Buisson & Dauzier, 1955b; Pitkjanen, 1960, 1962; Pitkjanen & Subin, 1961). As pointed out by Baker, Dziuk & Norton (1968), emphasis has too frequently been placed on the minimum time required for spermatozoa to reach the site of fertilization, as in those species in which mating precedes ovulation by a number of hours, rapid transport of spermatozoa to the ampulla may not be essential. A more meaningful assessment of the rate of sperm transport might be derived from measuring the interval between post-ovulatory deposition of semen in the female tract and sperm penetration of the eggs, despite the fact that this would refer only to live spermatozoa. In experiments in which the time of ovulation was controlled precisely by means of an injection of human chorionic gonadotrophin given during pro-oestrus (Dziuk, Polge & Rowson, 1964; Hunter, 1967a, b), spermatozoa were found in the zona pellucida of the egg within 2 h of intra-cervical insemination (Hunter & Dziuk, 1968). That considerable numbers of spermatozoa can be attached to the zona pellucida within 3 h of mating at the time of ovulation has been shown in subsequent studies (Hunter, 1972; Hunter & Hall, 1973, 1974a). In an attempt to define further the timing of entry of a population of spermatozoa into the Fallopian tubes, a technique of post-coital isolation of the tubes was employed (Hunter & Hall, 1974b). Animals were mated shortly after the
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time of induced ovulation, and the Fallopian tubes were separated under general anaesthesia from the uterine horns some 30, 45 or 60 min after mating. Penetrated eggs were found in all three groups within three hours of surgery, indicating that sufficient spermatozoa to fertilize a proportion of the eggs had entered the Fallopian tubes within 30 min of mating. By employing surgical deposition of whole semen directly into the uterus, it was also shown in this study that separation of the tubes from the uterus within 15 min of insemination permitted penetration of some eggs during the ensuing 3 h (Hunter & Hall, 1974h). This finding therefore supports the concept ofa rapid entry of sperm atozoa into the Fallopian tubes of oestrous pigs, and may also endorse the view that the rate of sperm ascent to the site of fertilization is accelerated around the time of ovulation (Du Mesnil du Buisson & Dauzier, 1955h; Ito et at., 1959) or towards the end of oestrus (Pitkjanen, 1960), possibly due to heightened activity in the muscular compartments of the tract. The latter situation would clearly have physiological advantages in reducing the risk of penetration of ageing eggs. NUMBERS OF SPERMATOZOA TRANSPORTED
Details of the numbers of spermatozoa recorded in the Fallopian tubes of sows and gilts have been given by various authors (Du Mesnil du Buisson & Dauzier, 1955a, b; Rigby, 1966; Baker & Degen, 1972); their results indicate that only a very small proportion of the massive number of spermatozoa deposited at mating or artificial insemination can be recovered from this region of the tract. The population of spermatozoa in the tubes may initially undergo considerable quantitative change, since Rigby (1964, 1966) has reported that sperm numbers increase until 12 h after insemination, and Pitkjanen (1960) noted an increase until 24 to 30 h after mating. But these findings contrast strongly with the study of First et at. (I 968b), in which the sperm population in the Fallopian tubes remained unchanged from i- to 24 h after insemination. If a sufficient volume of semen is inseminated so that fluid reaches the utero-tubal junction, the number of spermatozoa entering the tubes has been shown to be directly related to the concentration of spermatozoa in the inseminate (Rigby, 1964; Baker et at., 1968). This relationship has been interpreted as representing passage of an aliquot of semen to the site of fertilization (Baker et at., 1968). Thus the concentration of spermatozoa at the site of fertilization is likely to be related to the number of spermatozoa persisting at the utero-tubal junction (Rigby, 1964, 1966). Returning to our own approach of estimating quantitative aspects of sperm transport by noting the number of spermatozoa associated with the eggs, a brief summary has recently been given (Hunter, 1974). The mean number of spermatozoa around the small proportion of eggs with some sperm recovered two hours after insemination was 5'0 (range I to 14), increasing to 9'3 (range I to 80) at three hours after insemination (see Hunter & Dziuk, 1968). In a later study, the mean number of spermatozoa associated with the zona pellucida
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increased from 6·8 (range I to 25) at 3 h to 109'2 (range I to 466) some 6 h after mating at the time of ovulation (Hunter, 1972). By the time the two-celled stage is reached, two hundred or more spermatozoa may have penetrated the zona (Thibault, 1959; Hancock, 1961; Hancock & Hovell, 1961, 1962), and this number can increase substantially during the tubal descent of the embryo. These figures indicate that under conditions of mating or insemination close to the time of ovulation, a progressive increase in sperm numbers associated with the egg is occurring during the interval from activation of the secondary oocyte until passage of the developing embryo into the uterus. At the latter stage, the number of spermatozoa in the zona may be of the order of several hundred, and on occasions exceed four to five hundred (Hunter & Leglise, 1971). This significant increase in zona sperm could be invoked as evidence against the phagocytosis of spermatozoa in the Fallopian tubes during the 46 to 48 h that the embryos are in transit (see below). TRANSPORT OF LIVE VS. DEAD SPERMATOZOA
First et at. (I 968b) and Baker & Degen (1972) have reported that dead spermatozoa are transported through the utero-tubal junction into the isthmus. However, the former authors also claim that dead spermatozoa enter the Fallopian tube at the same "rate" as live spermatozoa. This claim stands in marked contrast to the work of Baker & Degen, in which consistently fewer dead spermatozoa were recovered from the upper uterine horns and tubes when gilts were inseminated with equal numbers of both. This latter study needs to be interpreted with caution, since it was conducted on hormone-treated prepuberal gilts inseminated whilst reclining on their backs under general anaesthesia, with sperm-collecting cannulae ligated into the reproductive tract. Nonetheless, Baker & Degen (1972) did remark that the mechanism whereby dead spermatozoa are transported through the utero-tubal junction is not well understood, although they suggested that fluid containing both live and dead spermatozoa is forced through the junction by uterine contractions. Such a mode of passage is unlikely to occur during oestrus, since pressure from the uterine side at this stage of the cycle would effectively close the junction (Andersen, 1928; Lee, 1928). Indeed, the uterine wall may rupture before fluid can be squeezed manually through the junction into the tube. These observations on the transport and persistence of dead spermatozoa in the female tract may be contrasted with the transport and survival of frozenthawed spermatozoa in gilts (PoIge, Salamon & Wilmut, 1970; Wilmut & Polge, 1971). In the latter situation, it has been noted that frozen-thawed boar spermatozoa rarely fertilize eggs when inseminated via the cervix, although high fertility has been obtained following surgical insemination directly into the tubes (Polge et at., 1970). Taking this finding, together with the fact that very few spermatozoa are recovered from the tubes after intra-cervical insemination of frozen-thawed material, it might be inferred that a degree of selection is occurring in the uterus or at the utero-tubal junction against such treated sperm a tozoa.
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ACKNOWLEDGEMENTS
Unpublished experiments reported in this paper were supported by a grant from the Agricultural Research Council, for which grateful acknowledgement is made. I am also indebted to a number of colleagues in Edinburgh for kindly commenting on portions of the manuscript. REFERENCES
ANDERSEN, D. E. (1928). Am. J. Anat. 42, 255. AUSTIN, C. R . (1964). Proc. 5th Int. Congr. Anim. Reprod. 3, 7. BAKER, R. D. & DEGEN, A. A. (1972). J . Reprod. Fert. 28, 369. BAKER, R. D., DZIUK, P.]. & NORTON, H. W . (1968). J. Anim. Sci. 27,88. BEDFORD,]. M. (1970). Proc. qj21st Mosbach Symposium , Berlin: Springer-Verlag. BISHOP, D . W. (1961). In Sex and Internal Secretions, Ch. 13, 3rd edn. ed. W. C. Young, Baltimor e: Williams & Wilkins. BLANDAU, R.]. (1969). In The Mammalian Oviduct, Ch. 5, ed. E. S. E. Hafez & R . ]. Blandau. University of Chicago Press. BRADEN, A. W. H ., AUSTIN, C. R. & DAVID, H. A. (1954). Aust. J . bioi. Sci. 7,391. BURGER,]. F. (1952). Onderstepoort J . vet. Res. Suppl. NO.2. CHANG, M. C. & PINCUS, G. (1951 ). Phy siol. R ev. 31, I. CORNER, G. W. (1923). Am. J. Anat. 32, 345. CROSS, B. A. (1959). In Recent Progress in the Endocrinology qj R eproduction, ed. C. W. Lloyd. New York: Academic Press. Du MESNIL DU BUISSON, F. & DAUZIER, L. (I955a ). Annis. Endocr. 16,413. Du MESNIL DU BUISSON, F . & DAUZIER, L . (I955b). C.R. Soc. B ioI. 149,76. DZIUK, P. ]., POLGE, C . & ROWSON, L. E. (1964). J . Anim. Sci. 23, 37. FIRST, N. L., SHORT, R . E. , PETERS,]. B. & STRATMAN, F. W . (1968a). J. Anim. Sci. 27, 1032. FIRST, N. L., SHORT, R. E ., PETERS, ]. B. & STRATMAN, F. W. (1968b). J. Anim. Sci. 27, 1037. GLOVER, T . D. (1 955). Vet. Rec. 67, 36. HAFEZ, E. S. E. (1973). Am. J. Obstet. Gynec. 115,7°3. HANCOCK,]. L. (I961).J. Reprod. Fert. 2, 307. HANCOCK,]. L. & HOVELL, G.]. R. (1961). Anim. Prod. 3,153. HANCOCK,j. L. & HOVELL, G.]. R. (1962). Anim. Prod. 4, 91. HUNTER, R. H. F. (1967a). Vet. Rec. 81, 21. HUNTER, R. H . F. (1967b). J. Reprod. Fert. 13, 133. HUNTER, R. H. F. (1972). J. Reprod. Fert. 29,395. HUNTER, R. H. F. (1974). Anat. Rec. 178, 169. HUNTER, R. H. F. & DZIUK, P . ] . (1968). J. Reprod. Fert. 15, 199. HUNTER, R. H. F. & HALL, j. P. (1973). J. R eprod. Fert. 35, 593. HUNTER, R . H. F. & HALL, ]. P. (1974a). J. expo Zool. 188,203. HUNTER, R. H. F. & HALL,]. P. (1974b). Anat. Rec. 180,597. HUNTER, R. H. F. & LEGLISE, P. C. (1971). J. Reprod. Fert. 24, 233 . ITo, S., K UDO, A. & NIWA, T. (1959) . Annis. Zootech., Ser. D , Suppl. p. 105. ITo, S., NIWA, T., KUDO, A. & MIZUHO, A. (1948). Zootech. Exp. Sta., Chiba, Res. Bull. 55,54. KEYE, j . D . (1923). Bull. Johns Hopkins Hosp. 34, 60. LEE, F. C. (1928). Bull. Johns Hopkins Hosp. 42, 335. LEWIS, L. L. (191 I). Okla. Agric. Exp. Sta. Bull., No. 96. McKENZIE, F. F., MILLER, ]. C. & BAUGUESS, L. C. (1938). Res. Bull. Mo. Agric. Exp. Sta. No. 279. McKENZIE, F. F., TERRILL, C. E., WARBRITTON, V. & NAHM, L . ]. (1935). Res. Bull. Mo. Agric. Exp. Sta. No. 358, 20. MANN, T . (1968). Proc. 6th Int. Congr. Anim. Reprod. 1,3. MANN, T., POLGE, C. & ROWSON, L. E. A. (1956). J. Endocr. 13, 133. MELROSE, D. R. (1963). Brit. vet. J. I19, 532. MELROSE, D. R. & O'HAGAN, C. (1961). Proc. 4th Int. Congr. Anim. R eprod. 4,855. NoYES, R. W. (1968). In Progress in Infertility. ed. S.]. Behrman & R . W. Kistner. Boston: Little, Brown. NOYES, R . W. (1972). Pathophysiolog}' of Gestation D isorders, 1,63.
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NoYES, R. W. & THIBAULT, C. (1962). Fert. SteriZ. 13,346. PARKES, A. S. (1960). In Marshall's Physiology of Reproduction, Chap. 9, vol. I, ed. A. S. Park('s. London: Longmans. PITKJANEN, I. G. (1960). Z. Obsc. Bioi. 21,28. PITKJANEN, I. G. (1962) . Vet. Med. 7,487. (Anim. Breed. Abstr. 30, 2699). PITKJANEN, I. G. & SUBIN, A. A. (1961). Svinovodstvo, 15,37. POLGE, C. (1956). Vet. Rec. 68,62. POLGE, C., SALAMON, S. & W1LMUT, I. (1970). Vet. Rec. 87, 424. RIGBY,j. P. (1964). Proc. 5th Int. Gongr. Anim. Prod. 4, 421. RIGBY,j. P. (1966).J. Reprod.Fert. II, 153. RIGBY, j. P. (1967). Vet. Rec. 80, 672. RODOLFO, A. (193¥). Philipp. J. Sci. 53, 183. RODOLFO, A. (1934b). Philipp. J. Sci. 55,13. SMITH, J. C. & NALBANDOV, A. V. (1958). Am. J. Vet. Res. 19, 15· THIBAULT, C. (1959). Annis. Zootech., Ser. D, Suppl. p. 165. THIBAULT, C. (1972). Int. J. Fert. 17, I. VAN DEMARK, N. L. (1958). Int. J. Fertil. 3, 220. WALLACE, C. (1949) . J. Endocrin. 6, 205. WALTON, A. (1960). In Marshal/'s Physiology of Reproduction. Ch. 8, vol. I, ed. A. S. Parkes. London: Longmans. WILMUT, I. & POLGE, C. (1971). J. Reprod. Fert. 25, 301. (Accepted for publication
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October 1974)
Aspects physiologique du transport du sperllle chez Ie porc dOlllestique, Sus scrofa I. DepOt du spenne et transport cellulaire (Hunter) ResUllle. Le processus de transport spermatique, migration et stockage ont ete examines pour Ie pore domestique chez lequel on pense que Ie volume d'ejaculation penetre dans I'uterus pendant Ie cOlt. Apres s'etre concentre sur la signification evolutive possible du site d'insemination, on porta son attention a la periode etendue de I'oestrus, a I'important volume du sperme depose, et au fait que la jonction utero-tubaire puisse etre baignee par Ie sperme avant que I'accouplement ne soit termine. La signification des trois "fractions" du sperme en relation avec la concentration et Ie passage des spermatozoldes a ete consideree, comme I'a ete I'importance de la jonction utero-tubaire et I'isthme de la trompe de Fallope dans la regulation du transport spermatique. Le degre de selection au niveau de la jonction utero-tubaire entre spermatozoldes vivants et morts, et entre les populations de cellules homologues et heterologues, a encore besoin d'eclaircissement. On a note des regions specialisees dans Ie stockage du sperme dans Ie tractus reproducteur feminin, tels que les diverticules de la jonction utero-tubaire et entre les plis de I'isthme caudal. De differents modes de repartition du sperme dans Ie tractus feminin ont ete decrits, mais l'implication des leucocytes polynucleaires dans la mobilisation des spermatozoldes a partir des trompes de Fallope est discutable. Com me pour Ie devenir du plasma seminal, ceci a ete poursuivi chimiquement, mais les determinations physiologiques a partir des etudes sur la capacite sont aussi considerees com me etant de valeur. En definitive, Ie fait est accentue de par les mesures temporelles et quantitatives du transport spermatique sont seulement biologiquement significatives lorsqu'elles sont considerees par rapport au reglage de l'ovulation et a la fecondation. Physiologische Aspekte der Sperlllawanderung bem dOlllestizierten Sus scrofa. I. Deponierung von Selllen und Zellenfortbewegung (Hunter) Zusall1ll1enfassung. Die Vorgange der Deponierung des Spermas, dessen Wanderung und seine Bewahrung beim Hausschwein sind untersucht worden. Man nimmt an, dass beim Koitus das gesamte Ejakulat in den Uterus gelangt. Nach Konzentration auf die mogliche evolutionare Signifikanz einer solchen Inseminationslokalisation wir auf die verlangerte Oestruszeit, auf die grosse Menge des deponierten Spermas und auf das Faktum hingewiesen, dass die utera-tubale Verbindung sich in einem Spermabad befinde, beY~r the Koitus beendet
SPERM TRANSPORT IN THE pIG
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sei. Die Signifikanz der drei "Fraktionen" im Sperma wurde in Betracht gezogen in Beziehung zur Konzentration und Passage der Spermazozoen; und desgleichen die Wichtigkeit der utero-tubalen Kommunikation und des Isthmus der Tube und ihre Bedeutung filr die Regulierung der Spermawanderung. Geklart muss noch werden, bis zu welchem Grade an der utero-tubalen Verbindungsstelle eine Aussonderung zwischen lebenden und toten Spermien und zwischen homologen und h eterologen Zellen stattfindet. Man fand spezialisierte Zonen, in denen Sperma in den weiblichen R eproduktionsorganen aufbewahrt wird z.B. die Diverticula der utero-tubalen Verbindungsstelle und in den Falten des caudal en Isthmus. Verschiedene Modalitaten der Disposition von Sperma vom weilblichen Genitaltrakt sind beschrieben worden, aber es ist fraglich, ob polymorph nuklare Leukozyten am Transport d er Spermien aus den Tuben beteiligt sind. Urn zu untersuchen, was aus d em Plasma im Semen wird, sind chemische Untersuchungen un tern ommen worden, doch dilrften physiologische Beurteilungen auf Grund von Untersuchungen der Capacitation ebenfalls wertvoll sein. Schliesslich wird betont, dass temporale und quantitative M essung der Spermabewegung nur dann von biologischer Bedeutung sind, wenn sie in Beziehung zur Zeit des Auftretens von Ovulation und Befruchtung betrachtet werden. Aspectos fisiologicos del transporte de esperlWl en el cerdo dOlllestico Sus sero/a. I. Deposicion del selllen y transporte de celulas (Hunter) ResulIlen. Se h an revisado los procesos del transporte, migracion y almacenaje de esp erma en el cerdo domestico, del cual se cree que la mayor parte del ejaculado entra eI utero durante eI coito. Tras concentrarla en eI posible significado evolutivo de este pun to d e inseminacion, se llama atencion al extenso periodo del oestro, a la gran cantidad del semen depositado y al hecho de que la juntura uterotubaria puede ser bafiada por eI semen antes de que se termine eI apareamiento. Se ha considerado eI significado de las tres "fracciones" en semen en relacion ala concentracion y paso de espermatozoos, asi como la importancia de lajuntura uterotubaria y eI istmo de la trompa d e Falopio en la regulacion del transporte de la esperma. El grado de seleccion en la juntura uterotubaria entre los esp ermatozoos vivos y muertos, y entre poblaciones de celulas homologas y h eterologas, necesita ser aclarado. Se han abservado regiones especializadas para eI almacenaje de la esperma en eI aparato reproductor de la hem bra, tales como las diverticulas de la juntura uterotubaria y entre los pliegues del istmo caudal. Se han descrito varios me todos de expulsion de la esperma del aparato femenino, pero la asistencia de leucocitos polimorfonucleares en la expulsion de expermatozoos de la tromp a d e Falopio es dudosa. En cuanto al destino del plasma seminal, se ha seguido desde eI pun to de vista quimico, p ero las evaluaciones fisiologicas de estudios sobre la capacitacion han probado ser tambien valiosas. Finalmente, se subraya eI hecho de que tanto las m edidas temporarias como cuantitativas del transporte d e la esperma solamente tienen significado biologico cuando se consideran en relacion al momenta exacto de ovulacion y fertilizacion.
