New morphological evidence for the synthesis and storage of renin in the human kidney: an ultrastructural immunocytochemical study.

Using an antibody to pure human renin and the technique of ultrastructural immunocytochemistry we have localized renin in the granular epithelioid cells of three juxtaglomerular apparatuses and one interlobular artery. The staining reaction of the cells was the same in both sites: we found that crystalline protogranules, rounded membrane-bound granules and storage granules intermediate in morphology all stained positively for renin. We also demonstrated immunoreactive renin in dilated cisternae of rough endoplasmic reticulum in the granular cells in both sites. We present these observations as morphological evidence that granular epithelioid cells synthesize and store renin both in the juxtaglomerular apparatus and in the larger arteries in the kidney.