The development of the human body; a manual of human embryology . ng the special structure of the serotinal compactumand concerning the origin of the intervillous space and itsrelations to the villi and the maternal vessels. From the surface of the compactum processes arise,termed septa, which project into the intervillous space,grouping the villi into cotyledons and giving fixation tosome of the roots of attachment of the villi (Fig. 75).Throughout the greater extent of the placenta the septado not reach the surface of the chorion, but at the periph-ery, throughout a narrow zone, they do come
The development of the human body; a manual of human embryology . ng the special structure of the serotinal compactumand concerning the origin of the intervillous space and itsrelations to the villi and the maternal vessels. From the surface of the compactum processes arise,termed septa, which project into the intervillous space,grouping the villi into cotyledons and giving fixation tosome of the roots of attachment of the villi (Fig. 75).Throughout the greater extent of the placenta the septado not reach the surface of the chorion, but at the periph-ery, throughout a narrow zone, they do come into con-tact with the chorion and unite beneath it to form a mem-brane which has been termed the closing plate. Beneaththis lies the peripheral portion of the intervillous space,which, owing to the arrangement of the septa in thisregion, appears to be imperfectly separated from the restof the space and forms what is termed the marginal sinus(Fig. 76). The probable origin of the intervillous space by theeffusion of blood from the maternal vessels into the sub-. Is aa O „ .- H « a ?sis o ?« B 5 ££ wa H H< S3 wo <:j PL, <2 w M a M^~ in a se a § o 3~ a^ 5 &§ .at •- H 2 a w .-rt O 53 S « a ^3 is n a ci 2 . - o <u rrt ** rl W I. fig to § d^ 4J <*-! (4-1 a! O O I58 THE DEVELOPMENT OF THE HUMAN BODY. stance of,the trophoblast and the subsequent corrosionof that layer has already been described, and if this be thetrue method of its development, then it is evident that thefetal villi are in direct contact with the maternal bloodcontained in the space. The uterine vessels become verymuch enlarged during pregnancy and those of the sero-tina communicate freely with the intervillous space, sothat a free circulation of the maternal blood through thespace occurs. The villi being completely immersed inthis constantly renewed blood, an osmotic interchangetakes place between the maternal blood of the space andthe fetal blood contained in the vessels of the villi, the
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
