pronephric tubule

pro·neph·ric tu·bule

an excretory unit of the pronephros, present only in vestigial form in human embryos.

pronephric tubule

any of the segmentally arranged excretory units of the pronephros in the early developing vertebrate embryo. The tubules open into the pronephric duct and communicate with the coelom through a nephrostoma. In humans and the higher vertebrates, the tubules are present only in vestigial form; in lower animals they are functional.