FCETAL NUTRITION: THE PLACENTA 431 



viscera, especially the Uver, have a considerable store of fat 

 which increases during suckling. 



Glycogen Metabolism. — The presence of glycogen in the 

 placenta of the rabbit was discovered by Claude Bernard ^ in 

 1859. He showed its increase and subsequent decrease during 

 pregnancy, and concluded from his observations that the 

 placenta carried out for the foetus, in the first half of intra- 

 uterine Ufe, the glycogenic function subsequently assumed by 

 the fcetal hver. Godet ^ described two areas of glycogen-con- 

 taining cells, one immediately underlying the fcetal vilU, the 

 other in the deeper part of the placenta. Maximow investigated 

 these ceUs at different stages of pregnancy ; he found glycogen 

 in the decidual cells of the vascular sheaths at the eighth day, 

 gradually increasing in amount and playing an important part 

 in the nourishment of the trophoblast. In the later stages 

 glycogen disappeared and the decidual tissue was transformed 

 into polygonal multinucleate cells rich in fat. Chipman recorded 

 detailed observations in a more complete age-series from the 

 eighth day to the end of gestation. He showed that glycogen 

 was always present in the maternal part of the placenta, but 

 never in the fcetal. Occurring in the decidual cells of both zones, 

 it increased and reached a maximum between the twelfth and 

 sixteenth days (Fig. 104) ; then it steadily diminished, and in 

 the last week only a few granules were found scattered in the 

 conglomerate masses of decidual cells. At the zone of separa- 

 tion, however, glycogen granules were still contained in decidual 

 cells. Chipman also examined the fcetal hver. In it he found 

 that glycogen appeared at the twenty-second day, and increased 

 rapidly and steadily in amount till the end of pregnancy. 



These results have for the most part been corroborated by 

 chemical analyses carried out by the writer, working in colla- 

 boration with Dr. W. Cramer.^ They determined quantitatively 

 the glycogen of the maternal placenta, fcetal Uver, and remainder 



^ Bernard, "Sur une nouvelle fonction du placenta," Gomp. Rend. Acad. 

 Sci., Paris, 1859. 



^ Godet, " Kecherches sur la structure intime du placenta du lapin," 

 Dissert. Inaug. d, la Fac. de M&d. de Berne, Neuveville, 1877. 



' Lochhead and Cramer, " The Glycogenic Changes in the Placenta and 

 the Foetus of the Pregnant Rabbit," Proc. Roy. Soc, London, B, vol. Ixxx., 

 1908. 



