The causes and treatment of abortion . atomical arrangements of the parts hereinvolved. Up to the second month the foetal and maternal FCETAL CAUSES. 97 portions of the future placenta are loosely connected with eachother. The villi are loosely implanted in the crypts or depressionsof the decidua between the tubular glands, and can Ije easily with-drawn. After the end of the third month the villi enlarge, andgive off many branches, consequently it is impossible to separatethe fcetal and maternal parts without lacerating them. To thenaked eye, a section of normal placenta presents an appearance
The causes and treatment of abortion . atomical arrangements of the parts hereinvolved. Up to the second month the foetal and maternal FCETAL CAUSES. 97 portions of the future placenta are loosely connected with eachother. The villi are loosely implanted in the crypts or depressionsof the decidua between the tubular glands, and can Ije easily with-drawn. After the end of the third month the villi enlarge, andgive off many branches, consequently it is impossible to separatethe fcetal and maternal parts without lacerating them. To thenaked eye, a section of normal placenta presents an appearancesomewhat like that of a sponge, made up in great parts of these villi are the irregular vascular spaces, or lacunae,which contain the maternal blood. The curling arteries bringthe blood to the placenta, and on their way, they not onlycontinue their tortuosities, but they divide and subdivide freely;this condition providing against a too sudden rush of blood tothe placenta. On entering the placenta, they push a thin layer. Fig. 14.—Section of a tumour showing fibroid structure (Priestley). or investment of decidua before them. At their finer subdivi-sions they are formed of only an endothelial lining and a littleconnective tissue. Finally, they open, without the interventionof capillaries, into the sinuses, lacunae, or maternal blood sinuses again open into veins, which are for the most partfound on and near the maternal surface of the placenta. Theblood returns by the slanting venous sinuses—the utero-placentalsinuses. Both the coiled arteries and slanting veins are tornacross when the placenta is separated from the uterus. Thearteries perforate the placenta obliquely, and are more numeroustowards the centre. They generally run along its external sur-face for about one-third of an inch before disappearing into theplacenta. The arteries do not anastomose. Eegarding the fcetalvessels, these, on arriving in the substance of the placenta, divide G 98 TF
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