Abolition of All Adrogen Target Organ Responses by the X-Linked Tfm (Testicular Feminization) Mutation
We have seen that both the primary (gonadal) and secondary (extragonadal) sex-determining meachanisms of mammals are founded on the principle of the inherently feminine basic embryonic plan. Accordingly, testis-organizing H-Y antigen has risen to the top of the regulatory hierarchy that determines the fate of embryonic gonads. As soon as fetal Leydig cells of the H-Y antigen-organized testis begin to synthesize and secrete testosterone, the second regulatory hierarchy for extragonadal sexual differentiation is set in motion. If there is to be a master regulatory gene product for the second hierarchical system as well, such a molecule must necessarily mediate the androgen-responsiveness of all the target cell types in the mammalian body. Because no sexual difference in the responsiveness to androgens has been noted either during the critical fetal stage or during the postpubertal stage, the above-noted molecule must be present in males and females alike. Thus, we realize that the two regulatory hierarchies are completely separated from and independent of each other.
KeywordsSertoli Cell Male Germ Cell Urogenital Sinus Wolffian Duct Testosterone Propionate
Unable to display preview. Download preview PDF.