Mesonephros

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mesonephros

[¦mez·ə′ne‚frōs]
(embryology)
One of the middle of three pairs of embryonic renal structures in vertebrates; persists in adult fish and is replaced by the metanephros in higher forms.

Mesonephros

 

wolffian body, a paired excretory organ in vertebrates.

The mesonephros consists of numerous twisting tubules that open at one end into the body cavity and at the other into the mesonephric (wolffian) duct. Each tubule has a lateral outgrowth —the malpighian corpuscle. In fish and amphibians, the mesonephros functions throughout life; in reptiles, birds, and mammals, including man, it functions only during the early stages of embryonic development, being subsequently replaced by the metanephros. At first the metanephros is metameric in structure, but this is lost as the organism grows. In the males of higher vertebrates, most of the mesonephros becomes an appendage of the testis and, with the wolffian duct, forms the vas deferens; in the females, the mesonephros is reduced.