[Morphology and physiology of organs of aquatic respiration in vertebrates: the gill].

The structure and function of gills has been studied in broad outline in fish and amphibia. In the fish gill, one can see two circulatory systems which are interconnected but relatively independent, which have distinct functions and which supply separate epithelia. The haemodynamic control of these two systems and the functioning of these epithelia has been examined with respect to the aquatic environment. In the amphibia, the gills continue to be functional in many cases, especially in the larvae and neotenic forms. In such cases the gills are adapted to function in concert with the lungs. When the latter are fully developed, the gills disappear. The author suggests that the role played by the gills in ionic regulation and acid-base balance in the amphibia and which has been somewhat overlooked is an important one.