Light and ultrastructural studies of renin granules in methacrylate and epon embedded kidneys

Abstract

The juxtaglomerular apparatus (JGA) is a distinct morphofunctional unit in the kidney and the main constituent cells are modified smooth muscle cells called juxtaglomerular (JG) cells. JG cells, located within the sleeve of afferent arterioles of glomeruli, are characterized morphologically by secretory granules. The granules contain renin, an enzyme of the reninangiotensin-aldosterone system that regulates blood pressure and electrolyte balance. The purpose of this report is to describe plastic embedding and staining procedures used to study renin granules by light and electron microscopy in a rat experimental model.The rats were orally administered enzyme inhibitors that induced hypertrophy and hyperplasia of JG cells resulting in increased storage and synthesis of renin granules. At necropsy, thin transectional slices of renal cortex were collected and specimens for light and ultrastructural examination were taken from adjacent cortical tissue in each rat. For histology, 2 mm thick slices of kidney were fixed in neutral buffered formalin.