File:Anatomy, descriptive and surgical (1887) (14763256924).jpg

Identifier: anatomydescripti1887gray (find matches)
Title: Anatomy, descriptive and surgical
Year: 1887 (1880s)
Authors: Gray, Henry, 1825-1861 Pick, T. Pickering (Thomas Pickering), 1841-1919, ed Keen, William W. (William Williams), b. 1837
Subjects: Human anatomy Anatomy
Publisher: Philadelphia : Lea brothers & co.
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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rmed of epiblastic cells (Fig. 88, a). The groove becomes deeper and deeper inconsequence of the further heaping up of the cells to form the ridge on either side.In this way the ridges eventually become two plates, the lamina? dorsales or medul-lary plates, which finally coalesce, and thus form a closed tube, the neural canal,lined by epiblast and having a covering of the same membrane (Fig. 88). Thiscoalescence first takes place in the middle of the embryo, then toward the cephalicend, and lastly at the caudal extremity. The lining of this tube is developed intothe nervous centres, the covering into the epidermis of the back and head. The In the spinal nerves the part in connection with the cord, including the ganglion, is formed frommesoblast, according to the most recent observation. (The spinal nerves do not arise as here stated,but are developed as outgrowths from the spinal cord. They are therefore of epiblastic, rather thanof mesoblastic, origin.) 104 GENERAL ANATOMY. Fig. 85.1
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jams to show the Development of the Three Layers of the Blastodermic (vesicle or) Membrane in transversesections: A, portion of the ovum with the zona pellucida and the germinal area. B, C, D, E, F. Q, differentstages of development; o, umbilical vesicle; a, amnion ; i, intestine; p, peritoneal cavity, bounded by thesplanchno-pleural and somato-pleural layers of mesoblast; 1, vitelline membrane ; 2, external blastodermiclayer (epiblast): 3, middle layer (mesoblast); 4, internal layer (hypoblast); 5, medullary laminae and groove;5, medullary canal; 6, epidermic laminae; 7, lateral flexures of the amnion; 7, the same almost in contact;8, internal epithelial layer of the amnion; 9, epidermis of the embryo; 10, chorda dorsalis; 11, vertebrallaminse; 12, protovertebrae proper; 13, muscular laminae; 14, lateral laminae ; 15, fibro-intestinal laminae; 16,cutaneous laminae; 17, internal fibrous layer of the umbilical vesicle; 18, muscular laminae extending tomeet the cutaneous; 19, external l

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