424 THE PHYSIOLOGY OF REPRODUCTION 



Swaen l ). It is formed of one or two layers of large connective 

 tissue cells which represent the first appearance of the decidual 

 cells. After the destruction of the superficial and glandular 

 epithelium, the trophoblast advances into the interglandular 

 tissue, the cells of which degenerate in turn and are absorbed. 

 The advance is most rapid where a capillary is met with. 



FIG. 102. Thickened ectoderm (ectoplacenta) in the rabbit, attached to 

 placental lobe and dipping more deeply at the position of the glands. 

 (Chipman.) 



ec, foetal ectoderm ; I, line of attachment of ectoderm ; d, fcetal ectoderm 

 dipping into placental gland ; g, terminal cul-de-sac of placental gland. 



The mucous membrane is now differentiated into two zones, 

 the intermediary region and the region of the uterine sinuses 

 (Duval). The intermediary region lies superficially. It is 

 closely packed with fusiform stroma cells and capillaries with 

 thin peri vascular sheaths of uninucleate decidual cells. "It 

 suggests a reaction of the maternal placenta to the ' parasitic ' 



1 Masquelin and Swaen, " Developpement du placenta maternel chez le 

 lapin," Bull, de VAcad. Roy. de Belg., 1879. 



