Mode of proliferation of gonadotrophic cells of the anterior pituitary after castration - immunocytochemical and autoradiographic studies.

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Abstract
There are 3 possibilities concerning the mechanism of increase in number of gonadotrophs in the anterior pituitary after castration: one is the cell division by mitosis of matured gonadotrophs, another is the differentiation of immature cells and the 3rd is conversion of some other cell types into gonadotrophs. To determine the above possibilities, light microscopic and EM examinations using a combination of immunocytochemistry and autoradiography were performed on normal and castrated adult male rats. Morphometry indicated that a highly increased population of gonadotrophs reacted with anti-LH[lutropin].beta. serum after castration. Increased numbers of mitoses and elevated incorporation of 3H-thymidine into the nuclear chromatin were observed in both anti-LH.beta. reactive cells and other pituitary cells after castration. EM immunocytochemical observations demonstrated the presence of immature cells with a few immunoreactive secretory granules in the castrated pituitary. Mitosis is a major factor for proliferation of gonadotrophs in the anterior pituitary after castration, but the possibility of differentiation from immature cells into gonadtrophs cannot be ruled out. The 3rd possibility was not proven.