THE I'lKTAI. \ir.MHK \\l.< "K V\V 



365 



According to the second ill ife view, which tii, 



defenders in VIK< :i<>w. TIKM:I;. Ki;< n. \\" M.DI:M:H. and 



others, the interrillous spaces ar* mit/iiii;/ /.* thun t/f / 

 enlarged ct'^l/liri/ blood-vessels oj ///"/ //""-, >sn. ( horion and 



decidua serotina early unite very intimately by means of their Mir- 



! hat no fissures are left l>ct\veen them. The villi ;row 

 the mucous tissue, the 

 Mipi'i-i'n-ial capillaries of 

 which enlarge to capa- 

 cious spar 



If this view is cor- 

 rect, the chorionic villi 

 will necessarily be sur- 

 rounded on all sides by 

 thin coverings of ma- 

 ternal tissue, or, since 

 a partial degeneration 

 of the covering would 

 certainly be possible, 

 there will of necessity 

 be at least a stage in the 

 development in which 

 such a covering will be 

 demonstrable. 



RCOLANI, KOMITI, p .^ 149 _ Dia&rammatic representation of the finer struc- 

 ture of the human placenta, after TCKNCB. 

 F, P.acenta foetalLs ; M. i;.-uv:ita uterina; ca, tortuous 

 artery ; up, vrin which conducts the blood away from 



the intervillous maternal blood-sinua (<f) ; x, a con- 

 tinuation of the maternal tissue over the vilh 



outside the layer tf (the metamorphosed epithelium 

 of the uterine mucoja), and is probably a conn 

 tissue membrane \\nli \.i--ular endotheliuin ; f, cords 

 of the placenta uterina. uhu-h unite with the tips of 

 some of the foetal villi (Haftwuiveln) ; ds, decidua 

 serotina of the placenta, 



and TURNER have in 

 fact, as has been pre- 

 viously stated, expressed 

 themselves to the effect 

 that probably the epi- 

 thelial layer resting 

 upon the connective- 

 tissue axis of the villi 

 is not the original chori- 

 onic epithelium derived from the serosa, but a o> \vring which arises 

 from the decidua placentalis a view the untenaMfne-ss of which has 

 ah cail v been shown. 



In the diagram which TURNER has sketched to illustrate hi 

 of the structure of the human placenta (fig. 149) the real original 

 villous epithelium is degenerated 



The cell-layer e' is the epithelium of the uterine murosa, into which 



