302 



HISTOLOGY. 



7 inches in diameter, i inch thick, and weighs a pound. The distal end 

 of the cord is usually but not always inserted near its center. From the 

 end ot the cord the amnion spreads over the placenta and is lightly adherent 

 to it; the free surface of the |amnion is smooth and glistening. The 



% 



am.' \ 



FIG. 345. A NORMAL HUMAN EMBRYO OF 10.0 MM REMOVED SURGICALLY WITH THE UTERUS, Six 



WEEKS AFTER THE LAST MENSTRUATION. 



The embryo has been exposed by cutting away most of the chorion, cho., and part of the amnion, am.; 

 u.c., umbilical cord; v., chorionic villi; y.s., yolk sac. 



chorion laeve, beginning at the placental margin, continues clear around 

 the cavity of the uterus and, as before mentioned, the amnion adheres 

 to it. The amniotic cavity is filled with fluid in which the embryo is 

 immersed. Shortly before birth the cervix dilates and the membranes 

 thus exposed, rupture. The amniotic fluid escapes and the child follows. 



