Understanding Mesonephros: The Temporary Kidney of Fetal Development

Mesonephros (Greek "middle kidney") is a term used in embryology to describe the intermediate stage of kidney development. During early embryonic development, the kidneys develop as two separate structures, called the metanephros and the mesonephros. The metanephros gives rise to the adult kidneys, while the mesonephros degenerates and disappears.

The mesonephros is a temporary organ that functions as a rudimentary kidney during early fetal development. It is capable of producing urine, but it is not as efficient as the adult kidneys and eventually atrophies and disappears as the fetus matures. The mesonephros is thought to play a role in the regulation of fluid balance and electrolyte homeostasis during early fetal development.

In humans, the mesonephros develops around 21 days after fertilization and begins to degenerate around 28 days after fertilization. By about 40 days after fertilization, the mesonephros has completely disappeared, and the metanephros has taken over as the primary kidney structure.