Seasonal changes in epididymis and the effects of FSH and testosterone in the spiny-tailed lizard,Uromastix hardwicki

Seasonal changes in epididymal weight and histology were studied in relation to testicular function in the adult spiny-tailed lizard, Uromastix hardwicki, over a period of 1 year. The eipdidymal weights, tubular diameter, and epithelial height increased in March, reaching a peak in April. This peak coincided with sperm maturation, elevated plasma testosterone levels, and release of sperm into the epididymis. The epididymal weights decreased in May following a sudden regression of the testis early in the month. The epididymal weights decreased further during June and remained low until February. The diameter of the duct and the height of the epithelial cells also decreased in May and the epididymal epithelium maintained a low histological profile from June to February. The fall testicular recrudescence was not accompanied by a change either in the weight or the histological structure of the epididymis. Administration of oFSH (0.1 mg) daily for 7 days during the sexually quiescent period induced a significant increase in the weight of the epididymis and epithelial height of the duct. Administration of testosterone alone, (2.0 mg) daily for the same period and under identical conditions, did not induce a change in the weight of epididymis or its histology. A possible permissive role of gonadotrophin in the hormonal regulation of the lizard epididymis has been suggested.