Mesonephros
![](/Images/godic/202501/27/Gray9863125.png")
![Enlarged view from the front of the left Wolffian body before the establishment of the distinction of sex.a, b, c, d. Tubular structure of the Wolffian body.e. mesonephric duct.f. Its upper extremity.g. Its termination in x, the urogenital sinus.h. The duct of Müller.i. Its upper, funnel-shaped extremity.k. Its lower end, terminating in the urogenital sinus.l. The genital gland.](/Images/godic/202501/27/Gray11073125.png")
![Section of the fold in the mesonephros of a chick embryo of the fourth day. Wolffian tubules are labeled to the right.](/Images/godic/202501/27/Gray11063125.png")
The mesonephros (Greek:middle kidney) is one of three excretory organs that develop in vertebrates. It serves as the main excretory organ of aquatic vertebrates and as a temporary kidney in reptiles, birds, and mammals. The mesonephros is included in the Wolffian body after Caspar Friedrich Wolff who described it in 1759. (The Wolffian body is composed of : mesonephros + paramesonephrotic blastema)