ON THE HISTOLOGY OF THE INTERSTITIUM AND THE OCCURRENCE OF STEROIDS IN THE STICKLEBACK (GASTEROSTEUS ACULEATUS L.) TESTIS

Publisher Website
Google Scholar
Abstract
This investigation was undertaken to ascertain the relationship between the testicular steroids of telecost fish and the detree of interstitial cell development in the gonad, during a limited period in the reproductive cycle. Testicular samples obtained from adult Gasterosteus aculeatus without nuptial dress caught during their spawning migration from salt to fresh water were examined histologically. The results indicated complete spermatogenesis with an immature interstitium. Males in this phase were made dominant by exposure to artificial summer temperatures and daylengths, and their gonads were compared with those of non-dominant specimens. Histological evidence indicated large interstitial cells in dominant, and small, developing Leydig cells in the testes of non-dominant fish. The percentage of non-tubular/total testis tissue, determined histometrically, indicated 20% and 32% respectively, in dominant and non-dominant specimens, probably reflecting changes in glandular activity. The testicular steroid content of dominant and non-dominant fish was compared by thin-layer purification of testes extracts and gas chromatographic identification and estimation. Testosterone, androstenedione, dehydroepiandrosterone (DHA) and progesterone occur in the testes of dominant fish. However, gonadal tissue of non-dominants contained no detectable amounts of testosterone, although androstenedione, DHA and progesterone were identified. The testicular steroid level of dominant and non-dominant specimens were compared, and indicated that dominants had 5-7 times the steroid level of non-dominants.