Granular and agranular cell counts in the juxtaglomerular apparatuses of rats with unilateral renovascular hypertension.

Counts were made of granular and agranular cells in the juxtaglomerular apparatuses of rats with unilateral renovascular hypertension, using light and electron microscopy. Both granular and agranular cells may appear binucleated; therefore, nuclear counts need to be corrected by 4 to 8 per cent to get true cell counts. The polar cushion (Polkissen) corresponds to the cells included in the juxtaglomerular cell count, which is really a nuclear count. Interstitial or inflammatory cells may lie close to the polar cushion and should be excluded from the counts. The polar cushions in sham-operated rats contained mostly agranular cells: less then 6 per cent of the cells were granular. Most of the granular cells lay outside the polar cushion in afferent and efferent arteriolar walls. With acute hypertension the cells in the polar cushion increased 26 per cent due to increases in both granular and agranular cells, with the result that 11 per cent of the cells were granular and 89 per cent agranular. The number of granular cells seemed to decrease with chronic hypertension while the number of agranular cells remained elevated. This suggests the agranular cells have a function which is independent of that of granular cells.