Int. J. Exp. Path. (I990) 7I, 639-646
The zona glomerulosa of the adrenal gland in rats with portacaval shunt. An ultrastructural and morphometric study L. Domenici Lombardo and *C. Cortesini Departments of Human Anatomy and Histology, Section of Histology and *III Surgical Clinic, University of Florence, Florence, Italy
Received for publication I 2 January I 990 Accepted for publication 3 April I990
Summary. The zona glomerulosa of the adrenal glands was studied histologically, ultrastructurally and morphometrically in portacaval shunt (PCS)-bearing rats 4 weeks after surgery. Compared with controls, the zona glomerulosa of rats with PCS showed an increase in thickness and a reduction in the number of lipid droplets in the cells of its inner portion, adjacent to the intermediate zone. Moreover, electron microscopy and morphometry of the cells of the inner portion revealed that qualitative and quantitative changes occur, consisting in a decrease in lipid droplets, an increase in the amounts of smooth endoplasmic reticulum and mitochondria, enlargment of the Golgi apparatus, and the appearance of numerous dense bodies at the vascular cell poles. All the above findings indicate that PCS induces an enhanced activity of the fully differentiated cells of the zona glomerulosa, which may be considered as an adaptive response-mediated by an activation of the renin-angiotensin system-to the lowering of the systemic pressure taking place in this experimental condition.
Keywords:
zona
glomerulosa cells, PCS, morphometry, ultrastructure.
Experimental studies on rats with end-to-side portacaval shunt (PCS) have shown that a marked reduction in the systemic blood pressure occurs 2-4 weeks after surgery. This is associated with an increased concentration of prostaglandin E (PGE) (Lauterburg & Bircher 1976) and y-aminobutyric acid (Moroni et al. I984), which in turn are known to have a hypotensive action (Lauterburg & Bircher 1976; Takahashi et al. 1958). Previous investigations have also revealed that a decrease in the blood pressure causes an activation of the renin-angiotensin sys-
tem and consequently an enhanced secretion of aldosterone (Vander I967; Laragh 1979), and that a rise in the plasma level of PGE is accompanied by an increase in the production of this hormone (Enyedi et al. I98I).
The results of the above functional investigations seem to indicate that the zona glomerulosa is stimulated following PCS. Our previous study of rat adrenal cortex corroborated such a view since a marked hyperplasia of the cells of the capsular region of the adrenal gland designed to evolve into
Correspondence: Dr L. Domenici Lombardo, Dipartimento di Anatomia Umana e Istologia, Sezione di Istologia 'E. Allara', Viale G. Pieraccini, 6, 50139 Firenze, Italy.
639
L. Domenici Lombardo & C. Cortesini zona glomerulosa cells could be seen (Dome- Eight electron micrographs at X 21 000 final nici Lombardo & Cortesini I988). magnification, chosen randomly and However, no data are available concern- obtained by four different sections of zona ing the secretory activity of the zona glomer- glomerulosa, distant from each other and cut ulosa cells following PCS. perpendicularly to the surface of the gland, The aim of the present study is to investi- were used per rat. For these evaluations, cells gate, ultrastructurally and morphometri- of the inner portion of the zona glomerulosa cally, the zona glomerulosa cells of rats 4 have been considered exclusively because weeks after PCS in order to determine they represent fully differentiated cells, whether qualitative and quantitative struc- unlike the cells of the outer portion of the tural changes occur which may indicate zona glomerulosa, in which there are blastic modifications in their secretory activity. cells and cells not yet fully differentiated (Domenici Lombardo & Cortesini I988) and whose involvement in aldosterone secretion Materials and methods still remains uncertain. Twelve adult male albino rats of the Wistar On each photograph, the volume density strain, weighing 250-300 g, were used in of mitochondria, smooth endoplasmic retithis study. They were housed under con- culum (SER) and lipid droplets comparttrolled conditions of temperature and humi- ments was measured by point counting dity, exposed to a natural dark-light cycle, using an isotropic square lattice with disand fed ad libitum with a standard diet. tance between test points of 0.47 jgm on Seven rats underwent end-to-side PCS section, over a whole surface of I I .- j3m2 on under ethyl ether anaesthesia (Lee & Fisher section per cell (Weibel 1 9 79). A total area of I96I) and were killed by decapitation 4 452 im2 was assayed in both PCS and weeks after surgery. At this time, the patency control rats. of the anastomosis was controlled and the The volume densities of the different cytoadrenal glands were removed. plasmic compartments were expressed as a The remaining five, age-matched, percentage of the entire cytoplasm. untreated rats were used as controls. Statistical analysis was performed using Small tissue fragments of the adrenal the two-tailed Student's t-test for unpaired glands were fixed by immersion in cold 4% values. P
The zona glomerulosa of the adrenal gland in rats with portacaval shunt. An ultrastructural and morphometric study L. Domenici Lombardo and *C. Cortesini Departments of Human Anatomy and Histology, Section of Histology and *III Surgical Clinic, University of Florence, Florence, Italy
Received for publication I 2 January I 990 Accepted for publication 3 April I990
Summary. The zona glomerulosa of the adrenal glands was studied histologically, ultrastructurally and morphometrically in portacaval shunt (PCS)-bearing rats 4 weeks after surgery. Compared with controls, the zona glomerulosa of rats with PCS showed an increase in thickness and a reduction in the number of lipid droplets in the cells of its inner portion, adjacent to the intermediate zone. Moreover, electron microscopy and morphometry of the cells of the inner portion revealed that qualitative and quantitative changes occur, consisting in a decrease in lipid droplets, an increase in the amounts of smooth endoplasmic reticulum and mitochondria, enlargment of the Golgi apparatus, and the appearance of numerous dense bodies at the vascular cell poles. All the above findings indicate that PCS induces an enhanced activity of the fully differentiated cells of the zona glomerulosa, which may be considered as an adaptive response-mediated by an activation of the renin-angiotensin system-to the lowering of the systemic pressure taking place in this experimental condition.
Keywords:
zona
glomerulosa cells, PCS, morphometry, ultrastructure.
Experimental studies on rats with end-to-side portacaval shunt (PCS) have shown that a marked reduction in the systemic blood pressure occurs 2-4 weeks after surgery. This is associated with an increased concentration of prostaglandin E (PGE) (Lauterburg & Bircher 1976) and y-aminobutyric acid (Moroni et al. I984), which in turn are known to have a hypotensive action (Lauterburg & Bircher 1976; Takahashi et al. 1958). Previous investigations have also revealed that a decrease in the blood pressure causes an activation of the renin-angiotensin sys-
tem and consequently an enhanced secretion of aldosterone (Vander I967; Laragh 1979), and that a rise in the plasma level of PGE is accompanied by an increase in the production of this hormone (Enyedi et al. I98I).
The results of the above functional investigations seem to indicate that the zona glomerulosa is stimulated following PCS. Our previous study of rat adrenal cortex corroborated such a view since a marked hyperplasia of the cells of the capsular region of the adrenal gland designed to evolve into
Correspondence: Dr L. Domenici Lombardo, Dipartimento di Anatomia Umana e Istologia, Sezione di Istologia 'E. Allara', Viale G. Pieraccini, 6, 50139 Firenze, Italy.
639
L. Domenici Lombardo & C. Cortesini zona glomerulosa cells could be seen (Dome- Eight electron micrographs at X 21 000 final nici Lombardo & Cortesini I988). magnification, chosen randomly and However, no data are available concern- obtained by four different sections of zona ing the secretory activity of the zona glomer- glomerulosa, distant from each other and cut ulosa cells following PCS. perpendicularly to the surface of the gland, The aim of the present study is to investi- were used per rat. For these evaluations, cells gate, ultrastructurally and morphometri- of the inner portion of the zona glomerulosa cally, the zona glomerulosa cells of rats 4 have been considered exclusively because weeks after PCS in order to determine they represent fully differentiated cells, whether qualitative and quantitative struc- unlike the cells of the outer portion of the tural changes occur which may indicate zona glomerulosa, in which there are blastic modifications in their secretory activity. cells and cells not yet fully differentiated (Domenici Lombardo & Cortesini I988) and whose involvement in aldosterone secretion Materials and methods still remains uncertain. Twelve adult male albino rats of the Wistar On each photograph, the volume density strain, weighing 250-300 g, were used in of mitochondria, smooth endoplasmic retithis study. They were housed under con- culum (SER) and lipid droplets comparttrolled conditions of temperature and humi- ments was measured by point counting dity, exposed to a natural dark-light cycle, using an isotropic square lattice with disand fed ad libitum with a standard diet. tance between test points of 0.47 jgm on Seven rats underwent end-to-side PCS section, over a whole surface of I I .- j3m2 on under ethyl ether anaesthesia (Lee & Fisher section per cell (Weibel 1 9 79). A total area of I96I) and were killed by decapitation 4 452 im2 was assayed in both PCS and weeks after surgery. At this time, the patency control rats. of the anastomosis was controlled and the The volume densities of the different cytoadrenal glands were removed. plasmic compartments were expressed as a The remaining five, age-matched, percentage of the entire cytoplasm. untreated rats were used as controls. Statistical analysis was performed using Small tissue fragments of the adrenal the two-tailed Student's t-test for unpaired glands were fixed by immersion in cold 4% values. P
