Influence of testicular secretions on tissue weight and on metabolic and enzyme activities in the epididymis of the rat

Preventing the entry of testicular secretions into the epididymis by ligating the efferent ducts resulted in reduced epididymal weight and an alteration in the distribution of carnitine throughout the segments. The metabolic activity of the distal regions of the duct was un-affected by ligation but some changes were apparent in more proximal regions, particularly in the initial segment. Inhibition of spermatogenesis by the administration of busulphan resulted in a loss of weight of the caput epididymidis similar to that caused by ligation of the efferent ducts, even though testicular fluid was not prevented from entering the epididymis. Treatment with busulphan also led to a reduction in androgen-binding protein (ABP) and to a lower activity of pyruvate carboxylase in the caput. Ligation of the efferent ducts in busulphan-treated animals prevented the entry of testicular fluid into the epididymis asjudged by the absence of ABP. Despite the absence of ABP, and hence any androgens normally associated with it, there was no appreciable change in the activity of androgen-regulated enzymes, indicating that sufficient androgen was reaching the epididymis by way of the peripheral circulation. However, the results suggest that, in addition to androgens, the testis normally produces some other component(s), possibly associated with spermatozoa, which are required for full maintenance of the weight of the epididymal duct and of meta-bolic activity in the more proximal regions