Textbook of normal histology: including an account of the development of the tissues and of the organs . oral recess,or stomodaeum, by a parti-tion, the pharyngeal plate,consisting of the opposed ectoderm and entoderm ; after the rupture of this plate the gut-tractcommunicates directly with the exterior through the oral cavity. Asomewhat similar process takes place at the lower part of the primitivedigestive tube, whereby the anus becomes established. For a con-siderable time the gut communicates with the cavity of the umbilicalvesicle through its duct. The several divisions of the primary dig
Textbook of normal histology: including an account of the development of the tissues and of the organs . oral recess,or stomodaeum, by a parti-tion, the pharyngeal plate,consisting of the opposed ectoderm and entoderm ; after the rupture of this plate the gut-tractcommunicates directly with the exterior through the oral cavity. Asomewhat similar process takes place at the lower part of the primitivedigestive tube, whereby the anus becomes established. For a con-siderable time the gut communicates with the cavity of the umbilicalvesicle through its duct. The several divisions of the primary diges-tive tube, its wall consisting of epithelial lining and supplementarymesodermic tissue, undergo differentiation and acquire distinctivecharacters, which, however, depend largely upon the differentiationof the embryonal epithelial layer. The division of the tube into particular regions begins with thestomach, which as early as the fourth week in the human embryois distinguishable as a spindle-shaped enlargement. With the sub-sequent rapid increase in the size of the organ, the tissues constituting. Transverse section of nine-day rabbit embryo, show-ing formation of primitive gut (g) by approximation ofventral plates composed of visceral layers of mesodermand entoderm (e) ; m, m, body-cavity bounded byparietal and visceral sheets of mesoderm ; n, neuralcanal. 188 NORMAL HISTOLOGY. Fig
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Keywords: ., bookauthorpiersolgeorgeageorgea, bookcentury1800, bookdecade1890
