MOLECULAR REPRODUCTION AND DEVELOPMENT 30346-352 (1991)
Sperm Selection Capacity of the Human Zona Pellucida ROELOF MENKVELD,l DANIEL R. FRANKEN,' THINUS F. KRUGER,l SERGIO OEHNINGER? AND GARY D. HODGEN2 'Tygerberg Hospital, Reproductive Biology Unit, Department of Obstetrics and Gynecology, Tygerberg, Republic of South Africa, and 2The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virgrnia Medical School, Norfolk, Virginia
Key Words: Sperm, Morphology, Zona pellucida, Human
both fertile and infertile men produce high numbers of morphologically abnormal spermatozoa (Fredricsson et al., 1977; Katz et al., 1982; Kruger et al., 1986; van Zyl et al., 1990). This phenomenon is of paramount clinical importance as sperm morphology is regarded by both investigators and practitioners as a n important prognostic factor in regard to pregnancy outcome. Negative correlations have been reported between the percentage of morphologically abnormal spermatozoa and natural and assisted reproduction (Kruger et al., 1986; Liu and Baker, 1988; van Zyl et al., 1990). Patients with teratozoospermia demonstrate poor sperm binding to the zona pellucida of intact ova (Liu et al., 1988) and to bisected zonae under hemizona assay (HZA) conditions (Franken et al., 1989), low in vitro fertilization (IVF) rates (Oehninger et al., 19881, and low ongoing pregnancies rates following IVF (Mahadevan e t al., 1987; Oehninger et al., 1988). Current information on the biology of human fertilization is derived from clinical observations obtained from fertilization in vitro (Mahadevan et al., 1987; Liu e t al., 1989) directly and from associated experimental evaluations of human gametes (Overstreet et al., 1976; Burkman et al., 1988). The HZA has become, among a wide array of functional tests for gametes, a useful and valuable experimental tool for physiological and cellular analysis of the early events requisite for gamete interaction leading to human fertilization (Burkman et al., 1988; Franken et al., 1989; Oehninger et al., 1989). In previous studies, we reported a significant linear relationship between the number of sperm tightly bound to the hemizona and the percentage of spermatozoa with normal morphology in the semen evaluated according to strict criteria (Franken et al., 1989; Menkveld et al., 1990). These findings suggest that a natural selection occurs against morphologically abnormal spermatozoa at the site of the zona pellucida. That is, under in vivo conditions natural barriers are
INTRODUCTION In contrast to many laboratory animal or livestock semen, human semen is virtually unique because of its heterogeneity in sperm morphology (pleomorphism);
Received April 10, 1991; accepted June 25, 1991. Address reprint requests to Dr. Sergio Oehninger, The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, 855 West Brambleton Avenue, Suite B, Norfolk, VA 23510.
Previous hemizona assay (HZA) reABSTRACT sults have illustrated a positive and significant correlation between the percentage of morphologically normal spermatozoa in the semen and the number of spermatozoa tightly bound to the zona pellucida. The present study was designed to evaluate the morphologic features using strict criteria of spermatozoa tightly bound to the zona pellucida. Semen samples of 4 normozoospermic and 11 teratozoospermic men were used to compare the percentage of normal spermatozoa in the semen with that found 1) after swim-up separation and 2) bound to the zona under HZA conditions. The mean (k SEM) % normal forms for normozoospermic men in semen, after swim-up and zona-bound spermatozoa were 21.5 k 1.6, 27.5 5 2.9, and 44.8 k 3.4, respectively. A significantly higher % of normal forms were found among zona-bound sperm compared to swim-up forms (p = 0.02) and seminal sperm (p = 0.02). The mean % of normal sperm forms present in semen, after swim-up and zona pellucidabinding for teratozoospermic men, were 3.7 f 0.9, 5.8 k 1.6 and 15.6 k 3.1, respectively. Significant differences existed between the % of normal sperm forms found in the swim-up and zona-bound spermatozoa (P =
Sperm Selection Capacity of the Human Zona Pellucida ROELOF MENKVELD,l DANIEL R. FRANKEN,' THINUS F. KRUGER,l SERGIO OEHNINGER? AND GARY D. HODGEN2 'Tygerberg Hospital, Reproductive Biology Unit, Department of Obstetrics and Gynecology, Tygerberg, Republic of South Africa, and 2The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virgrnia Medical School, Norfolk, Virginia
Key Words: Sperm, Morphology, Zona pellucida, Human
both fertile and infertile men produce high numbers of morphologically abnormal spermatozoa (Fredricsson et al., 1977; Katz et al., 1982; Kruger et al., 1986; van Zyl et al., 1990). This phenomenon is of paramount clinical importance as sperm morphology is regarded by both investigators and practitioners as a n important prognostic factor in regard to pregnancy outcome. Negative correlations have been reported between the percentage of morphologically abnormal spermatozoa and natural and assisted reproduction (Kruger et al., 1986; Liu and Baker, 1988; van Zyl et al., 1990). Patients with teratozoospermia demonstrate poor sperm binding to the zona pellucida of intact ova (Liu et al., 1988) and to bisected zonae under hemizona assay (HZA) conditions (Franken et al., 1989), low in vitro fertilization (IVF) rates (Oehninger et al., 19881, and low ongoing pregnancies rates following IVF (Mahadevan e t al., 1987; Oehninger et al., 1988). Current information on the biology of human fertilization is derived from clinical observations obtained from fertilization in vitro (Mahadevan et al., 1987; Liu e t al., 1989) directly and from associated experimental evaluations of human gametes (Overstreet et al., 1976; Burkman et al., 1988). The HZA has become, among a wide array of functional tests for gametes, a useful and valuable experimental tool for physiological and cellular analysis of the early events requisite for gamete interaction leading to human fertilization (Burkman et al., 1988; Franken et al., 1989; Oehninger et al., 1989). In previous studies, we reported a significant linear relationship between the number of sperm tightly bound to the hemizona and the percentage of spermatozoa with normal morphology in the semen evaluated according to strict criteria (Franken et al., 1989; Menkveld et al., 1990). These findings suggest that a natural selection occurs against morphologically abnormal spermatozoa at the site of the zona pellucida. That is, under in vivo conditions natural barriers are
INTRODUCTION In contrast to many laboratory animal or livestock semen, human semen is virtually unique because of its heterogeneity in sperm morphology (pleomorphism);
Received April 10, 1991; accepted June 25, 1991. Address reprint requests to Dr. Sergio Oehninger, The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, 855 West Brambleton Avenue, Suite B, Norfolk, VA 23510.
Previous hemizona assay (HZA) reABSTRACT sults have illustrated a positive and significant correlation between the percentage of morphologically normal spermatozoa in the semen and the number of spermatozoa tightly bound to the zona pellucida. The present study was designed to evaluate the morphologic features using strict criteria of spermatozoa tightly bound to the zona pellucida. Semen samples of 4 normozoospermic and 11 teratozoospermic men were used to compare the percentage of normal spermatozoa in the semen with that found 1) after swim-up separation and 2) bound to the zona under HZA conditions. The mean (k SEM) % normal forms for normozoospermic men in semen, after swim-up and zona-bound spermatozoa were 21.5 k 1.6, 27.5 5 2.9, and 44.8 k 3.4, respectively. A significantly higher % of normal forms were found among zona-bound sperm compared to swim-up forms (p = 0.02) and seminal sperm (p = 0.02). The mean % of normal sperm forms present in semen, after swim-up and zona pellucidabinding for teratozoospermic men, were 3.7 f 0.9, 5.8 k 1.6 and 15.6 k 3.1, respectively. Significant differences existed between the % of normal sperm forms found in the swim-up and zona-bound spermatozoa (P =
