The development of the human body; a manual of human embryology . y, producinga glomerulus, the wall of the tubule in this region becom-ing exceedingly thin to form a capsule of Bowman (, B, be). At first the glomerulus lies close to thesurface of the kidney,but as developmentproceeds it is gradu-ally carried deeperinto the cortical por-tion by the elongationof the portion of thetubule intervening be-tween the glomerulusand the primary renalvesicle. This elonga-tion affects at first theupper limb of the S,which is representedby the loop of Henle in the adult kidney, the portion between
The development of the human body; a manual of human embryology . y, producinga glomerulus, the wall of the tubule in this region becom-ing exceedingly thin to form a capsule of Bowman (, B, be). At first the glomerulus lies close to thesurface of the kidney,but as developmentproceeds it is gradu-ally carried deeperinto the cortical por-tion by the elongationof the portion of thetubule intervening be-tween the glomerulusand the primary renalvesicle. This elonga-tion affects at first theupper limb of the S,which is representedby the loop of Henle in the adult kidney, the portion between the loop andthe glomerulus forming the first, and that between theloop and the renal vesicle the second, convoluted tubule(Fig. 199, Q. In the mean time new tubules have arisen from thevesicle and have undergone a development similar to whatoccurs in the earlier formed ones, and the formation ofnew tubules continues until a large number has been pro-duced from each renal vesicle, these eventually elongatingto form the collecting tubules (Fig. 199, C). Up to the. Fig. 198.—Diagrams of Early Stagesin the Development of the Meta-nephric Tubules. t, Urinary tubule; Ur, ureter; v, renalvesicle.—(Haycraft.) 368 THE DEVELOPMENT OF THE HUMAN BODY. time when the urinary tubules begin to develop thereis no pelvis to the kidney, the ureter extending welltoward the center of the blastema before beginning tobranch and the branches thence extending to the cortex(Fig. 198). As soon as the tubules appear, however, theformation of the pelvis begins by what has been describedas an evagination of the primary branches of the ureter toform a common cavity, a process which is beginning to
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
