Histochemical activity of alkaline phosphatase and acid phosphatase in the epididymis of mature intact and androgen-deprived bulls.

The histochemical localization of alkaline phosphatase (ALP) and acid phosphatase (ACP) was determined in regions I to VI of the epididymis in mature intact, orchidectomized, and orchidectomized testosterone-treated bulls. The intensity of ALP activity was essentially the same in all regions; however, its localization varied depending upon the region. Although the stereocilia and luminal border of epithelial cells were strongly-positive in regions I to III, these were negative in regions IV to VI. The basement membrane and circumtubular smooth muscle cells were strongly ALP reactive in all regions. Epithelial ALP activity was abolished completely by orchidectomy; however, it was restored to normal concentration by testosterone treatment implying its dependence on circulating testosterone. The ACP activity was present in the epithelial cells of all regions with the strongest activity in the supranuclear region. Similar to ALP, ACP activity was markedly reduced in the epithelial cells by orchidectomy. However, in contrast to ALP activity, lost ACP activity was only minimally increased by testosterone treatment in all regions, except in region VI where it was restored to a normal concentration. These observations imply that although the epithelial ACP activity of region VI was mainly under the influence of circulatory testosterone, there may be other factors such as luminal androgens, testicular fluid, and sperm that may be important in regulating the ACP activity of regions I to V of the epididymis. The importance of ALP and ACP in the epididymal epithelium was discussed.