ELECTRON MICROSCOPIC STUDIES OF THE ANTERIOR PITUITARY GLAND OF CASTRATE RATS1

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Abstract
From adult female rats, castrated at 2 months of age and sacrificed at intervals of 6, 10, 20, 35 and 75 days thereafter, segments of the pituitary were fixed in buffered osmic acid and embedded in methacrylate; ultrathin sections were prepared for examination with an RCA electron microscope. Certain gonadotropic cells enlarged as early as 6 days following castration and underwent a regular sequential change in structure as the days after castration increased. These gonadotropes showed an increase in granular and mitochondrial content, enlargement of the Golgi apparatus and pronounced vesiculation of the cytoplasm. As the period after castration increased, the average size of the vesicles enlarged. At the same time the granule content diminished. In the late stages (35-and 75-days castrates) many of these cells were seen with just a fringe of cytoplasm surrounding 1 or several large vesicles. Other basophils were seen in the pituitaries of 35- and 75- day castrates. These cells were also greatly enlarged and showed varying degrees of vesiculation but were characterized by denser, more irregular nuclei and bizarre cytoplasmic forma-tions resembling filigree. Such cells are illustrated, and the possibility of their being another subvariety of gonadotropic cell is suggested. It is thought that these filigreed gonadotropes may be producing L.H. and that the previously described cells may be producing F.S. H. Acidophils which appear to be of 2 types were also noted. One cell contained smaller rounded granules; the other contained larger elliptical granular masses.