Abstract
The vas deferens can be used as a male hormone indicator because it is under the control of the internal secretion of the testis. After castration, definite regressive changes take place within 20 days in all animals. These changes involve Reduction in gross size through regression of the muscular layer of the vas; diminution of the amount of secretion in the lumen; reduction in epithelial height; loss of the cilia covering the epithelium; crowding together of the cells and obliteration of the cell walls; stratification of the nuclei; great reduction in the amount of cytoplasm in the cells; changes in the Golgi bodies involving loss in gross size and fragmentation of the Golgi material into rods or granules instead of the typical reticulum of the normal. All these changes can be prevented from developing in the castrated animal by daily injections of suitably potent male hormone prepared from the lipid fraction of fresh bull testes and dissolved in olive oil. If the changes have been allowed to develop, the vas can be built up to normal by daily injections of testis extracts. In animals castrated before puberty and allowed to regress for 110 days the vas can be built up to a normal functioning state by injections,[long dash]a process which involves bringing the undifferentiated duct to a normal adult state. Injections of pure olive oil fail to prevent castration changes, therefore the potent factor lies in the hormone itself.