Human renin granules: ultrastructural aspects.

The ultrastructure of human renin granules has been studied from a case of Bartter's syndrome. Renin bodies present roundish (R), lobulated (L) or sharply angulated (SA) shapes. The latter are indicative of the highest rates of renin synthesis and thereby of the greatest concentrations of the pressor enzyme. Their singular shape is consistent with the form monoclinic crystals assume when they grow in an isotrophic medium. R granules form owing to filling of Golgian vesicles by renin. R bodies may then coalesce for giving rise to transient L forms. Renin is released through leak from the containing granules into the intracellular space.