446 



THE PHYSIOLOGY OF REPRODUCTION 



of glandular detritus and the compact layer, which in turn form a 

 symplasma and undergo absorption. Thus the foatal structures reach 

 the spongy layer, in which the glandular culs-de-sac have expanded 

 to form large cavities separated by partitions, the mesenteriform 



FIG. 124. The angioplasmode of the dog at the thirtieth day of pregnancy. 

 (From Duval's " Le Placenta des Carnassiers," Jouni. d<> FAnat. et de la 

 Phys., 1893.) 



ms, Mesoblast ; lr, trophoblast ; ae, ectodermic arcades ; d, layer of 

 glandular detritus. 



lamella?. Gradually the roof of this layer is also absorbed by the 

 trophoblast, and the ectodermal arcades at the tips of the villi gain 

 a permanent attachment to the mesenteriform lamella^. At the same 

 time, by the further branching and penetration of the foetal nieso- 

 derm in the angioplasmode, the tissue is broken up into a series of 

 labyrinthine lamellae, which consist of a network of maternal vessels 

 clothed on each side by syncytial trophoblast. The meshes of the 



