Utente:Mikialba/Sandbox2: differenze tra le versioni
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[[Immagine:squola.png]]Questa Sandbox funge da "brutta copia" dei miei futuri articoli.
<big><center>'''''[[Polmone]]'''''</center></big>
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Riga 35:
==Origins==
The first lungs, simple sacs that allowed the organism to gulp air under oxygen-poor conditions, evolved into the lungs of today's terrestrial vertebrates and into the [[gas bladder]]s of today's fish. The lungs of [[vertebrate]]s are [[homology (biology)|homologous]] to the [[gas bladder]]s of [[fish]] (but not to their [[gill]]s). The evolutionary origin of both are thought to be outpocketings of the upper intestines. This is reflected by the fact that the lungs of a [[fetus]] also develop from an outpocketing of the upper intestines and in the case of gas bladders, this connection to the gut continues to exist as the [[pneumatic duct]] in more "primitive" [[teleost]]s, and is lost in the higher orders. (This is an instance of correlation between [[ontogeny and phylogeny]].) There are no animals which have both lungs and a gas bladder.
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