vi PKEGNANCY PARTURITION PUEKPERIUM 219 



furnished with numerous ramified villi, develops from the 

 ectoderm of the germinal vesicle (Fig. 78). Each villus is formed 

 of vascular connective tissue, covered with a protoplasmic stratum, 

 with nuclei in lines without distinct cellular boundaries, called 

 the syncytium of the chorion, covering an underlying stratum of 



h - 



FIG. 82. Uterus with ovum at the end of the second month of gestation. Longitudinal section. 

 Natural size. (From a preparation at the Obstetrical Clinic at Bale.) a, boundary between 

 decidua vera and reflexa ; b, decidua serotina ; c, chorion frondosum ; d, boundary between 

 decidua vera and reflexa ; e, decidua vera ; /, internal orifice ; g, cervix ; h, external orifice ; 

 i, decidua vera ; j, cavity of uterus ; k, cavity of ovum ; I, decidua vera. 



clearly defined cells called the cellular stratum of Langhans 

 (Fig. 85). At the third month a very distinct difference begins to 

 be seen between the chorionic villosities of the part corresponding 

 to the capsular region and those of the part standing in relation 

 to the basal or placental decidua. In the former the villi cease 

 to develop, becoming scarcer, smaller, and simpler, until the 



