478 THE PHYSIOLOGY OF RTilPRODUCTION 



Langhans' layer. Merfctens ^ ako found it in the decidua near 

 the ovum. Driessen ^ states that it is present in the superficial 

 and glandular epithehum of the uterus in the first month of 

 pregnancy ; around the ovum " in cells of doubtful origin," 

 glycogen is plentiful, but absent in the deeper parts of the de- 

 cidua ; in the viUi it is not found in the syncytium and Langhans' 

 layer, but is present in the cell-islands at the tips of the vilh, 

 and occasionally in the mesoblast. The total amount is, how- 

 ever, much smaller than in Rodents, and represents only about 

 0'08 per cent, by weight (Cramer ^). 



Fat. — Fat was first described in the human placenta by 

 Apfelstedt and Aschoff.* They found it during the second 

 month of pregnancy in the syncytium and Langhans' layer, 

 and in the decidual cells near the viUi. Eden ^ found fat in the 

 perinuclear protoplasm of the syncytium, and in Langhans' 

 layer and the stroma of the vilh. It is also present in the 

 capiUary waUs (Dastre ®). The appearances suggested to Eden 

 that " the placenta appears to be a storehouse of nutritive fat 

 just as is the liver." Minute discrete droplets were also present 

 in the decidual cells, and by the sixth month they had increased 

 in number. At full time the serotina still contained fat, but 

 "it is doubtful whether now it is a physiological deposit, as the 

 serotina shows many degenerative changes." At the same time, 

 a fatty degeneration of the decidua is probably pathological and 

 not a constant phenomenon (Klein '), and the fat globules in the 

 early 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 



^ Merttens, "Beitrage zur normalen und pathologischen Anatomie der 

 mensohliohen Placenta," Zeit. f. Oeb. u. Qynalc., vols. xxx. and xxxi., 1894-5. 



^ Driessen, " Ueber Glykogen in der Placenta," Arch. f. Qyndk., 

 vol. Ixxxii., 1907. 



' Cramer (A.), " Beitrage zur Kenntnis des Glykogens," Zeitschr. f. Biol. 

 vol. xxiv. 



* Apfelstedt and Aschoif , " Ueber bosartige Tumoren der Chorionzotten," 

 Aroh. f. Gynali., 1896. 



' Eden, " The Occurrence of Nutritive Fat in the Human Placenta," Proc. 

 Roy. Soc, London, vol. Ix., 1896. 



^ See Riohet's Dictionnaire de Physiologie, vol. vi.. Article "Foetus." 



' Klein, " Entwicklung und Riickbilduug der Decidua," Zeitschr. f. 

 Qeburtsh. u. Oynak., vol. xxii. 



