mesonephric

Mesonephric refers to the mesonephros, the transient middle kidney stage in vertebrate embryology. In humans, the mesonephros forms early in development and briefly functions as an excretory organ before the definitive kidney, the metanephros, assumes function. It consists of a network of mesonephric tubules that drain into a common duct, the mesonephric duct (Wolffian duct), which plays a key role in later reproductive development.

During embryogenesis, the mesonephros arises from the intermediate mesoderm and interacts closely with the mesonephric duct. Most mesonephric tubules regress as the metanephros forms, but some structures persist and contribute to the developing reproductive tract. In males, the mesonephric (Wolffian) ducts persist and differentiate under androgens into components of the internal male genitalia, including the epididymis, ductus deferens, and seminal vesicles. In females, these ducts largely regress, though remnants such as Gartner’s ducts can remain and occasionally form cysts.

The mesonephric stage also provides a temporary excretory function, contributing urine to amniotic fluid during early gestation. The transition to the metanephric kidney occurs as the definitive kidney forms and becomes functional, after which the mesonephros largely degenerates. The term mesonephric is used to describe structures associated with the mesonephros or Wolffian ducts, and is etymologically from Greek meso- 'middle' and nephros 'kidney'.