Double afferent arterioles of the rat renal glomerulus as studied by the injection replica scanning electron microscopic method.

One thousand eight hundred and fifty-six specimens of replicated rat renal glomerulus were examined under the scanning electron microscope, and an extremely rare anomaly of the glomerulus with double afferent arterioles was described. The double afferent arterioles arose separately from a terminal twig of the interlobular artery and reached the vascular pole of a subcapsular glomerulus which possessed a single efferent arteriole. Microdissection revealed that this glomerulus was composed of three fairly independent lobules of anastomosing capillaries. Microdissection also revealed that the double afferent arterioles were isolated from each other even in the glomerulus: the one supplied two lobules, while the other the third one only.