THE UTERUS DURING MENSTRUATION AND PREGNANCY 



241 



outlined cubical cells, and an outer syncytial trophoderm layer (Fig. 235). The 

 epithelium also forms solid columns of cells which anchor the ends of certain villi 

 to the maternal tissue. Islands, or nodes of epithelial cells, are attached to the 



Border cleft 



capsularis 



Fades 



intestinalis 



uteri 



Border zone 



Decidna 

 basalis 



Fades 



vesicalis 



uteri 



Apex, of 

 deddua 



Cervical 

 canal 



Posterior 



Up of os 



uteri 



FIG. 233. Section through a gravid uterus of twelve to fourteen days (Kollmann's Atlas). 



villi or lie free in the decidua basalis and represent portions of the primitive troph- 

 ectoderm. In the vessels of the chorionic villi the chorionic circulation of the 

 embryo is established. The blood-vessels of the uterus open into the intervillous 

 16 



