. Cunningham's Text-book of anatomy. Anatomy. l^>-> Pericardial coelom Alimentary canal when the umbilical orifice closes. The extra-embryonic portion is entirely obliterated when the outer surface of the expanding amnion fuses with the inner surface of the chorion (compare Figs. 77 and 78). The Intra-embryonic Coelom.—The intra-embryonic ccelom appears as a series of cleft-like spaces in the margin of the embryonic mesoderm. The spaces fuse together to form a f\-shaped cavity (Fig. 89) which separates the peripheral part of the embryonic mesoderm into a parietal or somatic, and a viscer
. Cunningham's Text-book of anatomy. Anatomy. l^>-> Pericardial coelom Alimentary canal when the umbilical orifice closes. The extra-embryonic portion is entirely obliterated when the outer surface of the expanding amnion fuses with the inner surface of the chorion (compare Figs. 77 and 78). The Intra-embryonic Coelom.—The intra-embryonic ccelom appears as a series of cleft-like spaces in the margin of the embryonic mesoderm. The spaces fuse together to form a f\-shaped cavity (Fig. 89) which separates the peripheral part of the embryonic mesoderm into a parietal or somatic, and a visceral or splanchnic, layer. The bend of the n -shaped cavity lies in the margin of the cephalic part of the embryonic region, and it has no direct communication with the extra- embryonic ccelom, but the caudal part of each stem of the cavity, on account of the disappearance of its lateral wall, soon opens, laterally, into the extra- "peritoneal canal embryonic CCeloni. The transverse portion of the f) -shaped cavity, which extends across the cephalic end of the embryonic area and connects the two limbs together, is the pericardial cavity. The adjacent part of each lateral limb of the cavity, the pleuro-pericardial canal, becomes a pleural cavity, and the lateral parts of the remaining portions Fig. 89.— Schema of Intra- unite ventrally, as the umbilical orifice closes, to form Embryonic Ccelom seen from tne single peritoneal cavity. ABOVE BEFORE THE FOLDING OF A °, i j n n j r, , n . , - -, , p ,, the Embryonic Area. ^s ^ne head told forms, the pericardial part ol the cavity is carried ventrally and caudally into the ventral wall of the fore-gut (Fig. 90). The mesoderm which originally formed its peri- pheral boundary, but which now lies in the cephalic boundary of the umbilical orifice, becomes thickened, and forms the septum transversum (Figs. 90, 91, 93). Alimentary - canal Peritoneal Cffilom. Pericardium Opening into pleuro- peritoneal canal Pleuro-peritoneal canal
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
