474 



THE HUMAN EMBRYO. 



surface, apparently on all sides. The villi were stated not to 

 penetrate into the uterine glands. The minute structure of 

 the ovum, or blastodermic vesicle as it may more properly be 

 called, was not ascertained. 



The chief additional points learnt from these further 



Fig. 175. — A longitudinal section of the Uterus with an Ovum in si 

 mated as about the thirteenth day. (After Kollmann.) x 1. 



c, esti- 



CV, cavity of ovum or blastodermic vesicle. C"W\ wall of blastodermic vesicle. 

 CZ, villi projecting from wall of blastodermic vesicle. DV, decidua vera. D"W\ 

 decidua serotina. DX, decidua refiexa. GrV, vagina. IT A, cavity of uterus. TJB, 

 dorsal wall of uterus. TJC, ventral wall of uterus. TJO, os uteri. TJK, uterine glands. 

 TJX, cervix uteri. 



specimens are : (i) that the rounded body described by Eeichert 

 as lying within the vesicle is made up of nucleated cells, and is 

 apparently solid, and attached to the embryonal or germinal 

 area ; (ii) that there is strong reason for thinking that the wall 

 of the vesicle really consists, not of a single layer of cells, but of 

 two layers, of which the inner one, regarded by Reichert as a 



