A System of midwifery : including the diseases of pregnancy and the puerperal state . into the common trunk of the umbilicalveins. This is the commencing vena portae. The amnion ( m m ) hasbeen freely opened to allow the embryo to escape, the caudal extremitybeing still within its cavity. The manner in which it is reflected toform the sheath of the umbilical cord is very clearly shown. Theumbilical cord is opened in its whole extent to show it- contents, in-cluding the canal of the urachus (pedicle of the allantois), which extends from the caudal extremity of the alimentary canal, closely ac-c
A System of midwifery : including the diseases of pregnancy and the puerperal state . into the common trunk of the umbilicalveins. This is the commencing vena portae. The amnion ( m m ) hasbeen freely opened to allow the embryo to escape, the caudal extremitybeing still within its cavity. The manner in which it is reflected toform the sheath of the umbilical cord is very clearly shown. Theumbilical cord is opened in its whole extent to show it- contents, in-cluding the canal of the urachus (pedicle of the allantois), which extends from the caudal extremity of the alimentary canal, closely ac-companied by the umbilical vessels, ami terminates at • in a either side are the umbilical arteries and veins, the arteries spring-ing from the Lower pari of the aorta, ami the veins passing upwards, to unite before entering the liver and mix their contents with the general circulation, at the point of confluence < o ). beneath the heart. The vein of the left side, which may be observed passing through the centre of 122 DEVELOPMENT OF THE EMBRYO AND FCETUS. [CHAP. the mesentery, is the permanent one. and is already much larger thanits fellow of the right side, which has been cut across at p p. Theheart (h ), with its four cavities and the aortic bulb, is separated fromtheliverbyan imperfect diaphragm. The Wolffianbody of the right side (/r) is shown passingfromthe heart to the inferior extremity of the its outer margin runs its excretory duct,which opens, along with its fellow of the otherside, into the cloaca behind the rectum. Thegreater relative size of the cephalic extremity ofthe embryo is a striking peculiarity which atonce attracts attention. The rudimentary eye(«) is remarkable, chiefly in respect of its lateralposition. In front of it is the right nasal fossa,and below it, at e, is the earliest trace of the in-ternal ear. The large bucco-nasal cavity, withthe three branchial arches beneath it, also attractspecial notice. Fig. 68 shows
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectobstetrics, bookyear1
