THE HAMSTER SERTOLI-CELL IN EARLY TESTICULAR REGRESSION AND EARLY RECRUDESCENCE - A STEREOLOGICAL AND ENDOCRINE STUDY

Utilizing stereological techniques, the hamster Sertoli cell at Stage VII of the spermatogenic cycle was examined for early signs of regressive changes after short-term photoperiod-induced testicular regression and for early signs of stimulation after short-term photoperiod-induced recrudescence. After 4-6 weeks of exposure to short photoperiod, germ cell degeneration was prominent but there were only minimal changes in Sertoli cell structure. These included a decline in volume of multivesicular bodies and in the surface area of mitochondrial membranes and adluminal plasma membrane, while no changes were noted in the other parameters measured. Of the endocrine changes, only plasma FSH levels had declined at this time and there were virtually no significant correlations between plasma FSH levels and the various structural parameters. The general lack of Sertoli cell changes in response to a short exposure to inhibitory photoperiod in the seasonally breeding hamster is similar to the early response to hypophysectomy in the none-seasonal rat. During early photoperiod-related recrudescence, testis weight, tubular lumen volume and interstitial parameters were increased. Significantly more preleptotene spermatocytes (about a 50% increase) were present in stage VII tubules, though adluminal germ cells did not increase in number. At this time some structural features of the Sertoli cells were enhanced in volume (cytoplasm, smooth and rough endoplasmic reticulum) and surface area (outer and inner mitochondrial membranes, smooth and rough endoplasmic reticulum and the basal compartment plasma membrane). Blood levels of FSH and testosterone were increased significantly but correlated only with rough endoplasmic reticulum, suggesting that initiation of the synthetic processes was imporant in reestablishment of spermatogenesis. Thus, similar to our findings in the Leydig cell, the structural responses of the Sertoli cell during regression and after recrudescence do not involve the same organelles. During re-stimulation, we suggest that hormonal stimulation affects primarily synthetic processes in the nucleus and rough endoplasmic reticulum of the Sertoli cell, and that its functions can be re-established only after these processes have been stimulated.