The practice of obstetrics, designed for the use of students and practitioners of medicine . fh Fig. 62.—Longitudinal (Sagittal) Sec-tion THROUGH AN EgG OF TriTON AT THE Beginning of Gastrulation. akOuter germ-layer; ik, inner germ-layer;jh, cleavage-cavity; vd, coelenteron; w,blastopore; ci2, yolk-cells; dl and vl, dor-sal and ventral lips of the blastopore.—{Hertwig-Mark.) JVC CH BH LM. PJV \.5i=- Fig. 63.—Sagittal Section of Frog Embryo showing the Three Layers. The blasto-pore now becomes the proctodeal opening and the neurenteric canal joining enteronwith neural canal.—{After Gotte.) BF,
The practice of obstetrics, designed for the use of students and practitioners of medicine . fh Fig. 62.—Longitudinal (Sagittal) Sec-tion THROUGH AN EgG OF TriTON AT THE Beginning of Gastrulation. akOuter germ-layer; ik, inner germ-layer;jh, cleavage-cavity; vd, coelenteron; w,blastopore; ci2, yolk-cells; dl and vl, dor-sal and ventral lips of the blastopore.—{Hertwig-Mark.) JVC CH BH LM. PJV \.5i=- Fig. 63.—Sagittal Section of Frog Embryo showing the Three Layers. The blasto-pore now becomes the proctodeal opening and the neurenteric canal joining enteronwith neural canal.—{After Gotte.) BF, Fore-brain; BH, hind-brain; BM, mid-brain; CH, notochord; M, mesoblast; NC,cavity of neural tube; NT, neurenteric canal; PN, pineal body; PT, point wherefuture mouth arises; TI, intestinal region of mesenteron; TP, pharyngeal region ofmesenteron; J/, proctodeal aperture; VK, liver; Y, yolk-cells. is possible in that animal, the formation of germ-layers has been more fullyand frequently studied in the chick than in any other species. The followingchanges, however, have been taken from the embryology of the rabbit, whichis tolerably well understood, because this mammal naturally has more resem- FORMATION OF GERM-LAYERS. 53 blance to man. The concentrated mass of cells above described at the poleof the ovum flattens out into a disc called the blastoderm, which is seen to KALEVIMA
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectobstetrics, bookyear1
