The development of the human body; a manual of human embryology . Rca Fig. 179.—Reconstructionof a Rabbit Embryo ofEight Days, with thePericardial Cavity LaidOpen. A, Auricle; Aob, aortic bulb;, auriculo-ventricularcommunication; Bp, ven-tral parietal recess; Om,omphalo - mesenteric vein ;Pc, pericardial cavity; Rca,dorsal parietal recess; sv,sinusvenosus; V, ventricle.—{His.) 336 THE DEVELOPMENT OF THE HUMAN BODY. splanchnic mesoderm in which they lie in contact withthe somatic mesoderm which forms the lateral wall ofeach recess. Fusion of the two layers of mesodermalong the course of the
The development of the human body; a manual of human embryology . Rca Fig. 179.—Reconstructionof a Rabbit Embryo ofEight Days, with thePericardial Cavity LaidOpen. A, Auricle; Aob, aortic bulb;, auriculo-ventricularcommunication; Bp, ven-tral parietal recess; Om,omphalo - mesenteric vein ;Pc, pericardial cavity; Rca,dorsal parietal recess; sv,sinusvenosus; V, ventricle.—{His.) 336 THE DEVELOPMENT OF THE HUMAN BODY. splanchnic mesoderm in which they lie in contact withthe somatic mesoderm which forms the lateral wall ofeach recess. Fusion of the two layers of mesodermalong the course of the veins now takes place, andeach recess thus becomes divided into two parallel pas-sages, which have been termed the dorsal (Fig. 180, rpd)and ventral (rpv) parietal recesses. Later the two veinsfuse in the upper portion of their course to form the begin-ning of the sinus venosus, with the result that the ventralrecesses become closed below and their continuity with the. Fig. 180.—Transverse Sections of a Rabbit Embryo showing theDivision of the Parietal Recesses by the Omphalo-mesentericVeins. am, Amnion; rp, parietal recess; rpd and rpv, dorsal and ventral divisionsof the parietal recess; vom, omphalo-mesenteric vein.—(Ravn.) trunk-cavity is interrupted, so that they form two blindpouches extending downward a short distance from theventral portion of the floor of the parietal cavity. Thedorsal recesses, however, retain their continuity withthe trunk-cavity until a much later period. By the fusion of the omphalo-mesenteric veins men-tioned above, there is formed a thick semilunar fold whichprojects horizontally into the coelom from the ventral wallof the body and forms the floor of the ventral part of theparietal recess. This is known as the septum iransver- THE PERICARDIUM. 337 sum, and besides containing the anterior portions of theomphalo-mesenteric veins, it also furnishes a passage bywhich the ductus Cuvieri, formed by the union of thejugula
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
