Search results
Results from the WOW.Com Content Network
The mesonephros persists and form 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) develops beginning during the sixth or seventh week, so that by the beginning of the fifth month only the ducts and a few of the tubules ...
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.
Unlike mammals, the kidneys of reptiles do not have a clear distinction between cortex and medulla. [43] The kidneys lack the loop of Henle, have fewer nephrons (from about 3,000 to 30,000), and cannot produce hypertonic urine. [3] [21] Nitrogenous waste products excreted by the kidneys may include uric acid, urea and ammonia. [55]
Scientists have grown kidneys containing mostly human cells inside pig embryos, an important step toward growing kidneys and potentially other human organs. Scientists take ‘pioneering steps ...
Pronephros is the most basic of the three excretory organs that develop in vertebrates, corresponding to the first stage of kidney development. It is succeeded by the mesonephros, which in fish and amphibians remains as the adult kidney. In amniotes, the mesonephros is the embryonic kidney and a more complex metanephros acts as the adult kidney ...
The African clawed frog or platanna, Xenopus laevis, was first widely used in laboratories in pregnancy assays in the first half of the 20th century. When human chorionic gonadotropin, a hormone found in substantial quantities in the urine of pregnant women, is injected into a female X. laevis, it induces them to lay eggs.
Standing over the pig rooms, VonEsch showed how pipes and vents were placed to allow maintenance and repair without any animal contact. It will take years of clinical trials to prove whether ...
The Hogben test procedure consisted of injecting a sample of women's urine into the skin on the back of the frog, specifically into the dorsal lymph sac. [16] Around 12 hours later, results could be seen. If the woman was pregnant, then the frog would be ovulating, and a small cluster of eggs could be seen at the rear end of the frog.