Electron microscopic studies on the formation of renal juxtaglomerular cell granules in the vitally stained mouse kidney.

Mouse renal juxtaglomerular cells (JGC) were vitally stained with neutral red, and then fixed with glutaraldehyde to study by electron microscopy. Ultrastructural observation showed a large number of characteristic low electron dense juxtaglomerular granules (JGG) or low dense granules (LDG) in the cytoplasm of JGC. Many LDG contained a flocculent material with a dense core, which was as dense as the contents of JGG. Two kinds of LDG were observed. One of LDG was surrounded by single membrane and partial membrane, and another was surrounded by double membranes. Some LDG did not contain electron dense flocculent material. LDG were surrounded by rough endoplasmic reticulum (r-ER). Alteration of Golgi apparatus and r-ER was observed in JGC. Golgi complex did not associate with JGG and LDG.