A system of midwifery . and symphysis pubis, occasion-ally leaving the integuments of the navel deficient, or, in other words,producing congenital umbilical hernia, or at the pubes a non-union of itssymphysis with a species of inversion of the bladder, the anterior wall ofthat viscus being nearly or entirely wanting. The cavity of the abdomen is therefore at first open to the vesiculaumbilicalis or yelk, but this changes as the abdominal parietes begin toclose in; in man and the mammalia merely a part of it, as above men-tioned, forms the intestinal canal, whereas, in oviparous animals the who
A system of midwifery . and symphysis pubis, occasion-ally leaving the integuments of the navel deficient, or, in other words,producing congenital umbilical hernia, or at the pubes a non-union of itssymphysis with a species of inversion of the bladder, the anterior wall ofthat viscus being nearly or entirely wanting. The cavity of the abdomen is therefore at first open to the vesiculaumbilicalis or yelk, but this changes as the abdominal parietes begin toclose in; in man and the mammalia merely a part of it, as above men-tioned, forms the intestinal canal, whereas, in oviparous animals the wholeof the yelk-bag enters the abdominal cavity, and serves for an early nu-triment to the young animal. Another change connected with the se-rous or outer layer of the germinal membrane is the formation of the am-nion. The foetal rudiment which from its shape has been called carina,now begins to be enveloped by a membrane of exceeding tenuity, forminga double covering upon it; the one which immediately invests the foetus. 64 DEVELOPMENT OF THE OVUM. is considered to form the future epidermis; the other, or outer fold, formsa loose sac around it, containing the liquor amnii. Whilst these changesare taking place in the serous layer of the germinal membrane, and whilstthe intestinal canal, &c., are forming on the anterior surface of the embryo,which is turned towards the ovum, by means of the inner or mucous layer,equally important changes are now observed in the middle or vascularlayer. In forming this fold, says Dr. A. Thomson, the mucous layeris reflected farthest inwards; the serous layer advances least, and thespace between them, occupied by the vascular layer, is filled up by a di-lated part of this layer, the rudiment of the heart. {Op. cit. p. 301.) Whilst this rudimentary trace of the vascular system is making its ap-pearance, minute vessels are seen ramifying over the vesicula umbilicalis,forming, according to Baers observations, a reticular anastomosis, which 5 is a port
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Keywords: ., bookcentury1800, booksubjectmidwifery, booksubjectpregnancycompl
