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The unipapillary kidney with a single renal pyramid is the simplest type of kidney in mammals, from which the more structurally complex kidneys are believed to have evolved. [17] [6] [18] Differences in kidney structure are the result of adaptations during evolution to variations in body mass and habitats (in particular, aridity) between species.
Some animals, like cnidarians, produce two germ layers (the ectoderm and endoderm) making them diploblastic. Other animals such as bilaterians produce a third layer (the mesoderm) between these two layers, making them triploblastic. Germ layers eventually give rise to all of an animal's tissues and organs through the process of organogenesis.
The first class of animals to become fully terrestrial without a larval stage were the reptiles, which were the first amniotes. [21] The kidney takes a key role in maintenance of the constant internal environment. The relative ionic composition of the extracellular fluid is similar between marine fish and all subsequent species.
The nephridium (pl.: nephridia) is an invertebrate organ, found in pairs and performing a function similar to the vertebrate kidneys (which originated from the chordate nephridia). Nephridia remove metabolic wastes from an animal's body. Nephridia come in two basic categories: metanephridia and protonephridia.
Coelenterata is a term encompassing the animal phyla Cnidaria (corals, true jellies, sea anemones, sea pens, and their relatives) and Ctenophora (comb jellies). The name comes from Ancient Greek κοῖλος (koîlos) ' hollow ' and ἔντερον (énteron) ' intestine ', referring to the hollow body cavity common to these two phyla.
The kidney of the frog is an opisthonephros. The kidneys are seen as two elongated, red organs in this image. The opisthonephros is the functional adult kidney in lampreys (cyclostomes), most fishes, and amphibians. [1] It is formed from the extended mesonephros along with tubules from the posterior nephric ridge. [2]
Size of a normal pig kidney (left) compared to a solitary pig kidney (right). Compensatory growth is a type of regenerative growth that can take place in a number of human organs after the organs are either damaged, removed, or cease to function. [1] Additionally, increased functional demand can also stimulate this growth in tissues and organs. [2]
In order to differentiate the use of the word mesenchyme in vertebrate embryology (that is, undifferentiated tissue found in embryonic true [ento-]mesoderm from which are derived all connective tissues, blood vessels, blood cells, the lymphatic system, and the heart) and the use in invertebrate zoology (a more-or-less solid but loosely organized tissue consisting of a gel matrix [the mesoglea ...