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EMBRYOLOGY 



membrane. The cylindrical epithelium of the mucous membrane of the 

 body of the uterus, soon after fecundation, becomes exfoliated, and its 

 place is supplied with flattened cells. This change is effected at the 

 sixth or the eighth week. The epithelium of the cervix retains its cylin- 



Fig. 227. Seventeen-days' gravid uterus, x I. From the Anatomical Museum of Johns Hopkins 

 University, Embryo drawn relatively too large (Williams). 



D.R., decidua reflexa ; D.S., decidua serotina; D.V., decidua vera; E, embryo; O.L., ovarian 

 ligament; R.L., round ligament. 



drical character, but most of the cells lose their cilia. The decidua 

 reflexa, which is thinner than the decidua vera, has neither bloodvessels, 

 glands nor epithelium. 



During the first periods of utero-gestation, the two layers of decidua 

 are separated by a small quantity of an albuminous and sometimes a 



