Pituitary - Gonad Relationship in the Male Snake Enhydris enhydris Schneider

The pars anterior of the pituitary gland of the estuarine snake Enhydris enhydris was studied in relation to the seasonal pattern of testicular activity, adopting histological techniques. Three types of basophils, type I, type II and type III, were distinguished in pars anterior of this snake adopting PAS-Orange G-Methyl Blue staining. Relying on the published literature the type I basophils (BI) are inferred as thyrotrophs, type II (BII) as FSH gonadotrophs and type III (BIII) as LH gonadotrophs, which are inferred to secrete TSH, FSH and LH, respectively. This inference is based on the observation that BI basophils underwent seasonal variation in abundance and structural features matching thyroid activity in relation to seasonal pattern of spermatogenesis, seasonal variation in BII basophils correlated directly with the seasonal spermatogenic cycle and seasonal pattern n in BIII basophils matched correlates of testicular interstitial cell activity. That the testicular activity is controlled by the pituitary gland in this snake was, further, substantiated by the regressive and degenerative changes in the seminiferous tubules. Thus, this study establishes the existence of pituitary-gonadal axis in this lizard, and there are indications that the testicular activity in this snake is under dual control of FSH and LH, as in the mammals.