. The chordates. Chordata. 642 Comparative Morphology of Chordates kidney is externally more or less deeply subdivided and therefore is described as "; The kidneys are more or less conspicuously lobulated in some ungulates—, ox, rhinoceros, elephant—and in some carnivores—, bear, otter (Fig. 488), seals, walrus. The number of lobules in the kidney of a walrus is estimated at between 300 and 400. Lobulation reaches its extreme in cetaceans, "each kidney appear- ing to be an aggregation of a multitude of small kidneys closely packed and contained within a single
. The chordates. Chordata. 642 Comparative Morphology of Chordates kidney is externally more or less deeply subdivided and therefore is described as "; The kidneys are more or less conspicuously lobulated in some ungulates—, ox, rhinoceros, elephant—and in some carnivores—, bear, otter (Fig. 488), seals, walrus. The number of lobules in the kidney of a walrus is estimated at between 300 and 400. Lobulation reaches its extreme in cetaceans, "each kidney appear- ing to be an aggregation of a multitude of small kidneys closely packed and contained within a single envelope" (A. B. Howell: "Aquatic. Fig. 187. A diagram illustrating the repeated branching of the collecting tubules in a nine-week (30 mm.) human embryo. Roman numerals indicate successive branchings. The diagram shows also the origin of excretory tubules from the nephrogenic tissue. (Redrawn from Rraus, after Kampmeier. Courtesy, Neal and Rand: "Chordate Anatomy," Philadelphia, The Blakiston Company.) Mammals"). The number of lobules in a kidney of the porpoise is estimated at above 400 (R. Owen). In some cases, and especially in the^maller kidneys, the embryonic- lobules may become closely compacted so that externally the adult kidney shows little or no sign of lobules. Internally, however, they may be recognizable. The human kidney is an example of this concealed lobulation, the number of internal lobules, corresponding to the "pyramids" (Fig. 85), ranging from 3 to 20. In many mammals, especially the smaller (, the cat), the kidney is simple, consisting of a single lobe—therefore not "; The smaller kidneys, not lobulated or with concealed lobulation, usually have the form of an indented ellipsoid—, bean-shaped (and a certain variety of bean is called "kidney-bean"). The common term "kidney-shaped" refers to this characteristic form, but some mam-. Please note that these images are
Size: 1827px × 1367px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollect, bookpublisherphiladelphiablakiston
