EFFECT OF HYPOPHYSECTOMY AND A LOW SODIUM DIET ON THE VOLUMES OF THE GLOMERULAR ZONE, FASCICULAR AND RETICULAR ZONES AND MEDULLA OF RATS
ABSTRACT Direct measurements of volume of the glomerular zone, fascicular and reticular zones and medulla were made in normal and hypophysectomized rats. All zones of the cortex and the medulla atrophied after hypophysectomy. However, while medullary and glomerular atrophy was proportional to the decrease in body weight, fascicular atrophy exceeded the loss in body weight. Hypertrophy of the glomerular zone occurred in rats fed a sodium deficient diet for 5 to 28 days beginning 14 days after hypophysectomy. Hence the volume of the glomerular zone is probably independent of the pars distalis, since the glomerular zone does not atrophy after hypophysectomy and can be stimulated to hypertrophy after it and the infundibular process are removed. Calculation of mass from areas in a mid-section by the Bahn formula and from direct measurements of volume yielded similar values for the mass of the fascicular zone. However, mean values for glomerular mass and for medullary mass were each significantly different. None the less, there was a high correlation between values, and the percent changes in mass of the glomerular zone resulting from the sodium deficiency were similar. Hence, the Bahn formula seems to be a useful shortcut procedure for detecting changes in the mass of the several regions of the cortex.