472 THE PHYSIOLOGY OF REPRODUCTION 



no evidence of such a process, and inclined to the opinion that 

 the material was dissolved by an enzyme before its absorption. 

 In the trophoblast they found that some of the vacuoles were 

 not yet filled with maternal blood, but contained a granular 

 coagulum which might, when liberated, have a digestive activity. 

 In either case, the extensive proliferation of the trophoblast 



FlG. 125. Section through embryonic region of ovum (after Peters). 



(From C. Webster's Human Placentation.) 



E.Sch., embryonic epiblast ; Ent., embryonic hypoblast ; Mes., mesoblast ; 

 D.S., umbilical vesicle ; A.H., amniotic cavity ; Ekt., chorionic -epiblast ; 

 Sp., space. 



appears to provide for the absorption of the necrosed tissue 

 around it, as well as for the flow of maternal blood into its 

 lacunae by the erosion of superficial capillaries. These two 

 objects accomplished, the greater part of the trophoblastic pro- 

 liferation disappears. 



Immediately after the excavation of the cavity the decidual 

 formation begins. Before this stage, the changes resemble those 

 that take place during the menstrual period. The vessels are 



