CYTOLOGICAL STUDIES ON THE HYPOPHYSECTOMIZED, RAT ADRENAL CORTEX: THE ALTERATIONS OFITS FINE STRUCTURE FOLLOWING ACTH ADMINISTRATION AND ON LOWERING THE Na/K RATIO1

Abstract

THIS work was undertaken as a sequel to an earlier electron microscopic investigation of the adrenal cortex in the normal rat (Lever, in press). The salient findings of this earlier study are as follows: (a) Throughout the cortex a subendothelial space separates the plasma membrane of the parenchyma! and sinusoidal endothelial cells, (b) Cells light and dark in respect of electron opacity are found in all zones and may represent phases in a secretory cycle, (c) In light cells large numbers of thin-walled polyhedral sacs lie in juxtaposition to the mitochondria, some of which are vacuolated. (d) Dark cells are characterised by large numbers of mitochondria, of compact internal form, lying in a relatively opaque background substance, (e) An osmiophile substance is either elaborated by or accumulates within the mitochondria, and in all cortical zones, forms are discernible intermediate between mitochondria per se and densely osmiophile bodies which are probably lipid droplets. The histology of the hypophysectomized rat adrenal has been widely investigated. Originally Smith (1930) reported that retrogression of the cortex was almost entirely responsible for the decrease in the rat adrenal weight following pituitary ablation. More selectively, Leblond and Nelson (1937) claimed that this cortical degeneration was most marked in the zonae fasciculata and reticularis. While Smith (1930) believed that a cytoplasmic reduction alone was responsible for cortical shrinkage, Crooke and Gilmour (1938) contended that there was also actual disappearance of cells in what they termed the “inner degenerative layers.” According to them, the “outer cortical zone” (by which they probably meant the glomerulosa) not only was of normal appearance but actually increased in depth, in the absence of the pituitary. Swann (1940) and Deane and Greep