504 THE PHYSIOLOGY OF REPRODUCTION 



stages represent an infiltration of fat into the decidual cells from the 

 maternal blood. 



From the absence of fat in the more superficial parts of the 

 syncytium, Hofbauer 1 suggests that it may be split up into fatty 

 acids and glycerine before absorption, and then re-synthesised by the 

 foetal placenta (Fig. 156). Thence it is carried by the blood in a 

 soluble form, and is again deposited in droplets in the heart, liver, 

 lungs, alimentary tract, and spleen of the fostus. In the later months 

 of pregnancy there is a considerable deposit of fat in the subcutaneous 

 tissue. 2 



Ss 



FIG. 156. Fat in a villus of the human placenta. (From Hofbauer's 

 liiiilniji',' (/-/ menscUichen t'lazenta, Braumiiller.) 



/., Fat globules in deeper layers of syncytium ; /'., fat in syncytium between 

 Langhans' cells ; /7>., fat in mesoblast ; /V., fat in vacuolated cell. 



Lipoids 



Bienenfeld 3 states that he found large quantities of lipoids in the 

 placenta in the earlier stages of pregnancy, but that as pregnancy 

 went on the lipoid content decreased. The quantity of lipoids was 

 exceptionally high in the condition of eclampsia. 



Respiration 



The respiratory exchange in the human fetus has been studied 



1 Hofbauer, '//", /;//y<> einer Bwlogie der mew/Jir/,,-,, JVazetita, Leipzig, 1905 

 (see above, pp. 475 and 543). 



2 See also Bondi, "Ueberdas Fett in der Placenta," A, </,. f. <V ///"//., vol. xciii., 

 1911 ; and Ballerini, " Histochemische Untersuchungen iiber Fettstoffe und 

 Lipoda im Plazentargewebe," Arch. f. <!>/,U-., vol. xcviii., 1912. 



3 Bienenfeld, "Beitrag zur Kenntnis des Lipoidgehaltes der Placenta," 

 Bwchem. Zeittch., vol. xliii., 1912. See also Ballerini, I,,-. eU, 



