( 385 ) 



a conjunctival svmplasm is formed, and, as was the case in the 

 hyj)erplastic process, not ever^wiiere simultaneously, so that small 

 partitions of svmplasm still surround more healthy groups. Outside 

 the placentai'y trophoblast all this goes on until a single mass 

 of epithelial and conjunctival symplasm is formed; within reach 

 of the placentary trophoblast, however, the trophoblast has already 

 penetrated before that time. During this degeneration also vessels 

 are opened, so that extravasates are not rare now and altered blood 

 is found against the trophoblast. 



The third process by which the trophoblast is connected with 

 the uterine wall, consists in the formation of hollow, one-layered 

 invaginations in the crypts, which trophablast papillae are covered 

 by caps of symplasm; between the crypts the trophoblast is extremely 

 thin by extension, often irrecognisable, also when later the forma- 

 tion of giant cells had advanced thus far : these latter are then very 

 long and narrow. 



Finally the placentary trophoblast (which now forms if it were 

 the keystone of the cupola of the diplotrophoblast and consists of a 

 distinct basal layer of cells of one cell thickness and an often 20 

 cells thick layer above it) now lays itself everywhere against the 

 papillae of the mesometral cupola of the placentary foetal chamber 

 cavity, which papillae are in progress of being degenerated ; the 

 trophoblast papillae are likewise still covered by the symplasm, 

 when between them this lias already been resorbed. 



Next comes the formation of a foetal syncytium from the super- 

 ficial layers of the thickened placentary trophoblast, the process 

 beginning above and centrally and proceeding centrifugally downwards; 

 the nuclei which at ürst were dark and small, become larger and 

 clearer, contain one big nucleolus and are clearly distinct from all 

 maternal elements. This syncytium everywhere penetrates into the 

 maternal tissue in strands, so that an intimate interweaving of 

 maternal and foetal tissue results, proceeding centripetally into the 

 papilla. Then everywhere "vacuoles" are formed in this mass 

 (probably now for the tirst time at the expense of maternal tissue), 

 which, when they become larger, bend the basal trophoblast layer 

 (cytotrophoblast) inwards and finally lill with maternal blood. The 

 allantois has meanwhile penetrated into the trophoblast papillae and 

 is divided into small lobes by the growth of pairs of bulges of 

 the cytotrophoblast. Foetal vessels soon penetrate freely into each 

 lobule. 



The priniordium of the placenta as a whole has no round shape, 

 the edges facing the connecting pieces of the foetal chambers are 



