. The comparative anatomy of the domesticated animals. Veterinary anatomy. TBE FCETU8. 895 CHAPTEE II. THE FCETAL ENVELOPES OF SOLIPEDS. We have seen, in the preceding chapter, that the vitelline membrane lined by the serous vesicle forms a complete shell around the developing ovum; and we have also noted that the layers of the blastoderm, in becoming meta- morphosed, constitute three membranous sacs, which contain the foetus. These various membranes are described as the envelopes or annexes of the foetus. There are also added to these the cord of vessels and the capillary ramifications which
. The comparative anatomy of the domesticated animals. Veterinary anatomy. TBE FCETU8. 895 CHAPTEE II. THE FCETAL ENVELOPES OF SOLIPEDS. We have seen, in the preceding chapter, that the vitelline membrane lined by the serous vesicle forms a complete shell around the developing ovum; and we have also noted that the layers of the blastoderm, in becoming meta- morphosed, constitute three membranous sacs, which contain the foetus. These various membranes are described as the envelopes or annexes of the foetus. There are also added to these the cord of vessels and the capillary ramifications which establish the relations that exist between the mother and the young creature. The annexes of the foetus comprise: 1, A membranous envelope exactly moulded on the uterus, and known as the chorion; 2, A second ovoid sac included in the first, and directly containing the foetus : this is the amnion ; 3, The allantois, a membrane formed of two layers spread over the inner surface of the chorion and the external face of the amnion, as well as covering the parts between these two envelopes; 4, A small pyrifovm bladder constituting the umhilical vesicle; 5, The placenta, a collection of vascular tufts which graft the young creature to the mother; 6, The umhilical cord, composed of vessels that attach the foetus to the envelopes surrounding it, and which ramify in the placental tufts. 1. The Chorion. (Pig. 422.) The outermost envelope of the ovum, the chorion is a vast membranous and perfectly-closed sac, whose shape exactly corresponds to that of the uterus. Fig. EXTEEIOK OF THE CHOKIAL SAO; MAEE. A, Body ; B, C, Cornua. It has a hodv and two cornua. The latter, when inflated, are plicated and bosselated like the cffioum, and are always unequal in volume: that m which the foetus is developed having by far the largest dimensions. , ^ ,^ The external face is studded with small red tubercles, formed by the. Please note that these images are extracted from scanned page images that m
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