A text-book of obstetrics / by J. Clarence Webster.

  • John Clarence Webster
Date:
1903
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of obstetrics / by J. Clarence Webster. Source: Wellcome Collection.

    76/810 page 66
    of fibrin may also be found between or around these villi. Such masses form other varieties of the Zel/knoten. The quantity of maternal blood in the intervillous space varies greatly. Where it is small the villi are closely massed together. Of all the tissues above noted the fetal elements form by far the greater portion. This can be clearly demonstrated if the chorionic vessels be injected with a carmin-gelatin solution through the umbilical arteries, the decidual layer ‘being afterward carefully removed by dissection, and the maternal blood washed out of the intervillous space. When the mass is placed in water the thickness of the placenta is seen to consist of a beautiful fron- dose arrangement of the injected villi. ; In such a preparation the fetal vessels may be distinctly traced. The large veins and arteries ramify in the chorionic membrane, the latter being more branched than the former. They dip down into the villus-stems, dividing mainly dichotomously and extend- ing into their various branches. In ate small villi capillaries only are found; in several the latter do not always extend throughout the whole length. In short ones there is usually only a single loop; in larger ones a tortuous arrangement of the vessels, form- ing a number of loops, between which an anastomosis may exist. I have already pointed out that the vessels vary in size in different specimens. Ordinarily the capillaries are small, but they may sometimes be dilated, allowing six or more blood-corpuscles to lie side by side. Occasionally a capillary may be small at one point and wide at another. Placental Infarcts.—Very frequently the placenta presents areas of various sizes, shapes, and colors, which are generally termed infarcts. Whitridge Williams has recently classified them as follows: Small whitish or yellowish fibrous-like areas, a few milli- meters in thickness, sharply marked off from the surrounding placental tissue. Wedge-shaped or irregularly rounded dull-white areas, of a erated fibrinous appearance. . Large portions of placenta showing this change. ‘i A vellowish- white rim, varying in width and thickness, extending around the margin of the “placenta on the fetal side under the amnion, forming a complete or partial Tine eet Lis condition is often termed ‘ “placenta marginata.’ In some cases this ring is situated more than half an inch internal to the edge. 5. Rarely a pinkish or brickdust-colored mass, of small or large size, found mainly near the maternal surface, but sometimes occupying the whole thickness of the placenta. These are known as “ ved infarcts.”
    digitised image 1
    digitised image 2
    digitised image 3