Effect of volume depletion on the afferent arterioles in the avian kidney

Peripolar cells in guinea pigs under experimental hyperplasia of juxtaglomerular cells induced by long-term, low-dose calcium condition

The peripolar cell was described in the glomeruli of sheep by Ryan et al. in 1979 and these cells have subsequently been detected in many species (Ryan et al. 1982; Gall et al. 1986; Hanner et al. 1980). The peripolar cells are located at the junction between the podocytes of the glomerular capillaries and the epithelial lining of Bowmann's capsule, encircling the hilar region of the glomerular tuft. Functionally, the peripolar cells have been considered to be a part of the juxtaglomerular apparatus but the precise nature of the cells has not been identified (Gardiner et al. 1985). Recently, it has been found that an antibody against rat urinary kallikrein reacts positively with sheep peripolar cell (Gall et al. 1984). This finding has led to the suggestion that the peripolar cells may influence the renin secretion through the kallikrein-kinin system. In our experiments with long-term low-calcium condition accompanied with hyperplasia of juxtaglomerular cells the peripolar cells were easily detected. The results suggests that the increase in the number of peripolar cells is closely related to the hyperplasia of juxtaglomerular cells.

Processing of colloidal gold particles in the glomerular mesangium and macula densa of the duck kidney

Bovine-serum-albumin coated colloidal gold particles were injected intravenously into healthy, adult domestic ducks. The fate of these tracer particles was followed in a time-sequence up to 4.5 days in the renal glomerular mesangium--distal tubule macula densa junction with transmission electron microscopy. The bulk of particle aggregates is 'trapped' in the mesangial channel system, phagocyted by mesangial cells, exocyted back into the mesangial channels, transported extracellularily towards the vascular hilus, rephagocyted by macula densa cells and expelled into the tubular lumen. This process requires about nineteen hours in the experimental model chosen, although it continues to take place to a much lower extent even 4.5 days after administration of the tracer. This mode of macromolecular excretion may be of interest in connection with the pathogenesis of several forms of glomerulonephritis.

Peripolar cells in the avian kidney

Four white leghorn chickens were injected with furosemide (20 mg per kg body weight) three times at 12 h intervals and the kidneys fixed by perfusion after 36 h. Five chickens were injected with DOCA (desoxycortone trimethylacetate, 75 mg per kg body weight) three times at 12 day intervals and the kidneys fixed by perfusion after 36 days. Serial sections from the kidneys of these two groups of birds were made and the number of peripolar cells recorded. These recordings were compared with the number of peripolar cells in four normal, untreated chickens. A significant increase in the number of peripolar cells was recorded in the furosemide treated group. No significant change was seen in the DOCA treated group. However, in the DOCA-group heavily granulated podocytes were found. No distinct morphological difference was found between the granules in the podocytes and the granules in the peripolar cells. A possible lysosomal nature of the peripolar cell granules is discussed.