. A text-book of embryology for students of medicine [electronic resource]. Embryology; Embryology. DEVELOPMENT OF THE KIDNEY AND URETER. 239 and in the following manner : The nephrogenic tissue into which the kidney evagination penetrates shows a differentia- tion into two zones—an inner one, immediately surrounding the primitive renal pelvis, consisting of epithelioid cells, and an outer zone of less differentiated mesenchyme. Soon after the appearance of the small diverticula which evaginate from the primitive renal pelvis and which are designated the primary collecting tubules (which latte
. A text-book of embryology for students of medicine [electronic resource]. Embryology; Embryology. DEVELOPMENT OF THE KIDNEY AND URETER. 239 and in the following manner : The nephrogenic tissue into which the kidney evagination penetrates shows a differentia- tion into two zones—an inner one, immediately surrounding the primitive renal pelvis, consisting of epithelioid cells, and an outer zone of less differentiated mesenchyme. Soon after the appearance of the small diverticula which evaginate from the primitive renal pelvis and which are designated the primary collecting tubules (which latter correspond with the " primitive renal vesicles" of Haycraft), the nephrogenic tissue breaks up into smaller cell-masses, each such mass surrounding a primary collecting tubule (Fig. 123, mk). This part of the nephro-. Fig. 123.—Section through the kidney of human fetus of seven months (from Felix, after Schreiner): Sr, collecting tubules of which three are shown, each with its cap of metanephrogenic tissue, mk; in relation with each is an early uriniferous tubule, the three latter, a, b, c, each showing a different stage of development—a, showing beginning of expansion; b, evagination at hk; c, S-shaped stage, bk indi- cating development of Bowman's capsule. genie tissue Schreiner calls the metanephrogenic tissue by way of distinction from the remaining part of this mesenchymal aggregation which, from its relation to the development of the mesonephros, is called the mesonephrogenic tissue. Each primary collecting tubule, after becoming bulbous at its end, divides into two tubules, each one of which in turn divides into two, this process of division being repeated several times. These tubules become the adult straight collecting tubules. The branching of the primary collecting tubules continues to the time of birth ; or until the fifth fetal month, according to Hamburger. In the development of the secreting tubules the inner zone of nephrogenic or metanephrogen
Size: 1928px × 1296px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpubli, booksubjectembryology
