FCETAL NUTRITION: THE PLACENTA 415 



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

 to form large cavities separated by partitions, the mesenteriform 

 lamellae. Gradually the roof of this layer is also absorbed by 



FIG. 98. The angioplasmode of the dog at the thirtieth day of pregnancy. 

 (From Duval's "Le Placenta des Carnassiers," Journ de I'Anat. et de la 

 I'hys., 1893.) 



ma, mesoblast ; tr, trophoblast ; ae, ectodermic arcades ; d, layer of 

 glandular detritus. 



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

 villi gain a permanent attachment to the mesenteriform lamellae. 

 At the same time, by the further branching and penetration 



