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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. The metanephric blastema mostly develops into nephrons, but can also form parts of the collecting duct system.
Diagram shows the sequential development and degeneration of the pronephros and mesonephros, and the induction of the ureteric bud and metanephric mesenchyme during kidney development in mammals. The development of the kidney proceeds through a series of successive phases, each marked by the development of a more advanced kidney: the ...
Early kidney structures include the pronephros and mesonephros, whose complexity, size and duration can vary greatly between vertebrate species. [1] The adult kidney, also referred to as the metanephric kidney, forms at the posterior end of the intermediate mesoderm after the degeneration of previous, less complex kidney structures. [1]
The metanephric kidney is the definitive (permanent) mammalian kidney, which persists in adults. ... [39] caused by the loss of the condensed mesenchyme of the ...
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 mechanism of multicystic dysplastic kidney is a result of an abnormal induction of metanephric mesenchyme. This could be a result of a formation difficulty of the mesonephric duct. Some mutations in genes associated with renal dysplasia (in syndromes) have been determined.
In embryonic day 10.5, embryos lacking Osr1 expression fail to grow a ureteric bud that migrates into the uncompacted metanephric mesenchyme. [14] The lack of inductive signals from the ureteric bud combined with a downstream reduction in Pax2 expression results in apoptosis and agenesis of the kidney. [14]
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 ...