in taxon Mammalia portal system renal portal system UBERON:0010195 function not well understood renal-portal system A portal system that transports blood returning from capillary beds within tail or hindlimbs through paired renal portal veins that empty into capillaries within the kidneys. AAO:0010518 portal system of kidney present in all classes of vertebrates except mammals; the mammalian kidney has a low pressure vascular network that may be its counterpart Part of the circulatory system in which the veins of the hindlimb combine to form the pair Jacobson's veins which receive many small vesicles from the kidney and also collects blood from the oviducal vein.[AAO]