Role of the epididymis in reabsorption of inhibin in the rat.

The effects of efferent duct ligation, orchidectomy and orchido-epididymectomy were compared at 36 h. This showed that the rat epididymis is capable of maintaining a negative feedback control of FSH secretion. Epididymal extracts contained a substance of tubular origin capable of reducing FSH secretion. This substance is a protein and is found in the caput region but not in the caudal region of the epididymis. A new role can be assigned to the head of the epididymis: that of reabsorbing, together with testis fluid, the inhibin produced by the seminiferous tubules, which thus passes into the bloodstream and provides a feedback regulation of plasma FSH.