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The development of the kidney proceeds through a series of successive phases, each marked by the development of a more advanced kidney: the archinephros, pronephros, mesonephros, and metanephros. [1] The pronephros is the most immature form of kidney, while the metanephros is most developed. The metanephros persists as the definitive adult kidney.
The metanephros is the definite, permanent, but yet immature kidney. It arises from two directions. On one hand, the precursor of the ureter buds from the Wolffian duct, while on the other hand, the precursor of the renal tubules develop from the metanephrogenic blastema.
Metanephros is the most complex form of kidney. [44] Each metanephric kidney is characterized by a large number of nephrons and a highly branched system of collecting tubules and ducts, [28] that open into the ureter. [48] Such branching in the metanephros is unique in relation to the pronephros and mesonephros. [44]
The mesonephros persists and forms the anterior portion of the permanent kidneys in fish and amphibians, but in reptiles, birds, and mammals, it atrophies and for the most part disappears rapidly as the permanent kidney (metanephros) begins to develop [2] during the sixth or seventh week. By the beginning of the fifth month of human development ...
The metanephros develops from the ureteric bud, which is an outgrowth on the caudal part of the nephric duct, [170] [171] and the metanephrogenic blastema, which is part of the intermediate mesoderm surrounding the ureteral bud. [172] [173] The development of metanephros begins with the induction of a metanephrogenic blastema by the ureteric bud.
The metanephros are primordia of the permanent kidney. [29] Function. The nephron, shown here, is the functional unit of the kidneys. Its parts are labelled except ...
The metanephrogenic blastema or metanephric blastema (or metanephric mesenchyme, or metanephric mesoderm) is one of the two embryological structures that give rise to the kidney, the other being the ureteric bud.
In amniotes, the mesonephros is the embryonic kidney and a more complex metanephros acts as the adult kidney. [1] Once a more advanced kidney forms, the previous version typically degenerates by apoptosis or becomes part of the male reproductive system. The pronephros develops from the intermediate mesoderm, as do the later kidneys.