Electron Microscopic Studies on the Adrenal Medulla and Adrenal Cortex of Hypertensive Rats : 1. Spontaneously Hypertensive Rats

Abstract

Spontaneously hypertensive rats (OKAMOTO and AOKI) (SHR) in the prehypertensive stage (40-60 days after birth), initial stage of hypertension (4-6 months after birth) and advanced stage of hypertension (more than one year after birth) were used in an electron microdscopic study of the fine structure of the zona fasciculata of the adrenal cortex and the noradrenaline storing cells of the adrenal medulla and compared with normal control rats of corresponding ages. The following results were obtained. 1. The number of noradrenaline storing granules within the adrenal medullary cells and the number of vesicles representing the postsecretory state were signiflcantly larger in the SHR than in normal rats at each stage. On ultra-thin slices, the number of granules was about I .3 times the control and the number of vesicles about 1.4-2.6 times the control. The granules revealed variations in size. 2. The cells In the zona fasciculata of SHR showed an increase in the number of RNA granules and mitochondria as compared with normal rats at each stage. An increase in number and distention of the smooth surfaced endoplasmic reticulum was pronounced, and closely resembled the finding recognized following ACTH administration. 3. The cells in the zona glomerulosa of SHR at initial stage of hypertension showed a slight increase in the number of mitochondria as compared with normal rats. Morphological changes in the zona reticularis were not recognized through electron microscopy at each stage.