Distribution Patterns of Urinary Tracts and Renal Blood Vascular Systems of the Eel Anguilla japonica

Abstract

Each of collecting tubules distributed superficially on the ventral trunk kidney is a complex of several members connected with the ipsilateral ureter after converging on some representatives. Secondary tubules derived from them diverge repeatedly at the periphery into urinary tubules which show remarkable windings on the way to distal glomerula. Blood supply by the renal artery which comes from the dorsal aorta is performed principally with a by-pass system. Each trunk of distal branches of the renal artery mostly connects via the anastomosis with the renal portal vein derived from the caudal vein. After sending off the most anterior right branch near the divided area, the caudal vein together with this branch becomes to be the paired renal portal vein. At the same area, many branches of the renal portal vein seem to connect via capillary networks with the renal vein which converges on the right posterior cardinal vein. Anastomoses exist further at the follwing vein juctions: anterior branch of the caudal and hepatic portal; right renal portal and hepatic portal; renal portal and renal; left and right posterior cardinal. The last paired veins are provided besides with a certain number of commissures on the way to anterior cervical kidney.