The extrinsic and intrinsic blood vessels of the mesonephros in the sheep have been studied with special reference to the so-called “giant glomerulus”. The latter is precocious in its development as compared with the Malpighian bodies caudal to it. The angioblastic preglomerular tissue is the important factor in determining the shape and vascular connexions of the Malpighian bodies. The latter vary greatly in size and shape, possess multiple efferent vessels and show a marked degree of linkage and fusion together. The tubules are surrounded by a plexus of sinusoidal veins in which feature the mesonephros differs fundamentally from the metanephros.
The early vessels of the metanephros and the origin of the renal and spermatic arteries are briefly discussed.