REPRODUCTION. 87 
MIcROSCOPIC STRUCTURE OF THE PLACENTA. 
This varies somewhat for different forms, though, in that 
there is a supporting matrix, minute (capillary) blood-vessels, 
and epithelial coverings to the foetal and maternal surfaces, the 
several forms agree. 
ef 
CEMA 
=e 
, Fie, 99. 
Fras. 95 to 101.—Diagrammatic representation of the minute structure of the placenta (Foster 
and Balfour, after Turner). F footal; M, maternal placenta; e, epithelium of chorion ; 
e, ehrnelats of maternal placenta; d, foetal blood-vessels ; d’, maternal blood-vessels ; 
villus. 
Fia. 95.—Placenta in most generalized form. 
Fig. 96.—Structure of placenta of a pig. 
Fie. 97.—Of a cow. 
Fie. 98.—Of a fox. 
Fic. 99.—Of a cat. 
The pig possesses the simplest form of placenta yet known. 
The villi fit into depressions or crypts in the maternal uterine 
mucous membrane. The villi, consisting of a core of connective 
