mesonephros /-nef″rəs/ pl. mesonephra, mesonephroi [Gk, mesos + nephros, kidney] , the second type of excretory organ to develop in the vertebrate embryo. It consists of a series of twisting tubules that arise from the nephrogenic cord caudal to the pronephros and that at one end form the glomerulus and at the other connect with the excretory mesonephric duct. The organ is the permanent kidney in lower animals, but in humans and various other mammals it is functional only during early embryonic development and is later replaced by the metanephros, although the duct system is retained and incorporated into the male reproductive system. Also called mesonephron, middle kidney, wolffian body. See also metanephros, pronephros. −mesonephric, mesonephroid, adj.
