Electron Microscopic Investigations of the Adrenal Cortex

Abstract

The purpose of our electron microscopic study is to observe and make clear the interrelationship between the mitochondria and the other organelles in the adrenal cortex in situ from the standpoint of the biosynthesis of steroid hormones. The results are summarized as follows: The mitochondria are divided into 3 types: the ‘I,’ the ‘Intermediate’ and the ‘Ila, b’ types. The mitochondria of the I type have a lamellar structure or membranelike projections. The Ha type mitochondria appear as a honeycomblike structure in a horizontal section, and each of them contains many microtubules. On the other hand, there are some mitochondria in which a few microtubules fuse due to the disappearance of their mutual partitions, and they are named the lib type. By ACTH administration, Ila type mitochondria increase in size and number, and, at more advanced stages, the open-form mitochondria increase. The endoplasmic reticulum is developed markedly by ACTH administration. On the contrary, following hypophysectomy, the mitochondria of zona fasciculata decrease markedly in size and number, but type I mitochondria are not influenced. Chorionic gonadotropin administration mainly stimulates the inner layer of the zona fasciculata and the outer layer of the zona reticularis, and then lib type mitochondria increase. As for both light and dark cells, there is a cyclic functional correlation between them, and the dark cells are interpreted as hyperfunctional cells.