FCETAL NUTRITION: THE PLACENTA 



485 



Tupaia. In Tiipaia Jan in ',<,< also the placentation is moditied by 

 the characteristics of the uterine mucosa. Hubrecht x has shown that 

 two specialised areas, the " Hafttiecke," exist before the attachment 

 of the trophoblast. They lie one on each side, about midway between 



*^^IHEr & J f ' 



^"^B .'.'": 



Dl *a * '9 - . f . 



FIG. 144. Orifice of a uterine gland of the mole with trophoblast ic dome. 

 (From Vernhout's " Veber die Placenta des Maalwaira," Amit. H<ii". 

 vol. v., 1894.) 



///., Uterine mucous membrane ; >n'., uterine epithelium ; p/., plasmo<lill;i>t : 

 cy., cytoblast ; g.s., gland secretion. 



the mesometrial and anti-mesometrial regions, and are recognised by 

 the absence of glandular ducts. The deeper parts of the glands 

 persist till the end of pregnancy, but none open on the modified areas. 

 The uterine epithelium again disappears at the points of contact 

 with the blastocyst over the " Haftflecke." There the tmphoblast 

 becomes thickened, and its cells enlarge and penetrate between the 

 epithelial cells, which fuse to form a symplasma. This is quickly 

 absorbed by the trophoblast, which continues {<> thicken, and now 



1 Hubrecht, "Ueber die Entwicklung der Placenta von 7*"/v/'"x uml 7'<'/x//",'' 

 Inter i'i. ('"/><//: of Zool., Cambridge, 1898. 



