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The kidneys in reptiles are located mainly in the caudal part (away from the head) of the abdominal cavity [49] [50] or retroperitoneally (behind the peritoneum) in the pelvic cavity in the case of lizards. [49] Reptile kidneys are commonly elongated [51] with color ranging from light to dark brown. [52]
In many cases the cast skin peels backward over the body from head to tail, in one piece like an old sock. A new, larger, and brighter layer of skin has formed underneath. [5] [7] An older snake may shed its skin only once or twice a year, but a younger snake that is still growing may shed up to four times a year. [7]
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 ...
Basal non-mammalian synapsids ("mammal-like reptiles") traditionally also sort under class Reptilia as a separate subclass, [27] but they are more closely related to mammals than to living reptiles. Considerations like these have led some authors to argue for a new classification based purely on phylogeny, disregarding the anatomy and physiology.
Urology addresses diseases of kidney (and urinary tract) anatomy: these include cancer, renal cysts, kidney stones and ureteral stones, and urinary tract obstruction. [ 7 ] The word “ renal ” is an adjective meaning “relating to the kidneys”, and its roots are French or late Latin.
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.
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Snake scales are formed by the differentiation of the snake's underlying skin or epidermis. [7] Each scale has an outer surface and an inner surface. The skin from the inner surface hinges back and forms a free area which overlaps the base of the next scale which emerges below this scale. [8] A snake hatches with a fixed number of scales.