. The development of the human body : a manual of human embryology. Embryology; Embryo, Non-Mammalian. 282 DIGESTIVE TRACT AND GLANDS forward and eventually meet in front of the original anal orifice. From the mesoderm of the circular elevation thus produced the ex- ternal sphincter ani muscle is formed, and it would seem that so much of the lower end of the rectum as corresponds to this muscle is formed by the inner surface of the elevation and is therefore ectodermal. The definitive anus being at the end of this terminal portion of the gut is therefore some distance away from the posi- tion
. The development of the human body : a manual of human embryology. Embryology; Embryo, Non-Mammalian. 282 DIGESTIVE TRACT AND GLANDS forward and eventually meet in front of the original anal orifice. From the mesoderm of the circular elevation thus produced the ex- ternal sphincter ani muscle is formed, and it would seem that so much of the lower end of the rectum as corresponds to this muscle is formed by the inner surface of the elevation and is therefore ectodermal. The definitive anus being at the end of this terminal portion of the gut is therefore some distance away from the posi- tion of the original cloacal nc Fig. 170.—Reconstruction of the Hind End of an Embryo mm. Long al, Allantois; b, belly-stalk; cl, cloaca; cm, cloacal membrane; i, intestine; n, spinal cord; nc, notochord; , postanal gut; ur, outgrowth to form ureter and metanephros; w, Wolffian duct.—(Keibel.) It will be noticed that the digestive tract thus formed consists of three distinct portions, an anterior, short, ectodermal portion, an endodermal portion representing the original archenteron, and a posterior short portion which is also ectodermal. The differentia- tion of the tract into its various regions and the formation of the various organs found in relation with these may now be Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original McMurrich, J. Playfair (James Playfair), 1859-1939. Philadelphia : P. Blakiston's son & co.
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Keywords: ., bookautho, bookcentury1900, bookdecade1910, booksubjectembryology
