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.

    74/810 page 64
    branches to supply the villi; sometimes a large branch disappears abruptly, its ramifications not being visible. Great variations are noticed as regards the course of the branches. Minot states that the more eccentric the insertion of the cord the more symmet- rically are the vessels distributed; the nearer the center the less their symmetry. Occasionally remains of the umbilical duct and vesicle may be noticed under the amnion, close to the cord. The former is a minute sac; the latter a thread-like stalk. Very rarely these may be accompanied with unobliterated omphalomesenteric vessels. F1G. 46.—Placenta at full term, showing superficial distribution of blood-vessels (Minot). At the edge of the placenta the amnion, chorion, and decidual layers extend outward, forming the so-called ‘‘ membranes.” Occasionally the place of transition is not the edge of the pla- centa, but a ring around the fetal surface of the organ, internal to the edge. A good idea of the general plan of the placenta may be obtained from the study of transverse sections across it. On the fetal side are the amniotic and chorionic membranes. On the maternal side is a very thin layer of decidual tissue, which may be wanting in places. These meet and are in close apposition at the placental edge; here the decidual layer may often spread for a short distance on the under surface of the chorionic membrane. Between the decidual and chorionic layers there is thus a large
    digitised image 1
    digitised image 2
    digitised image 3