The formation, regression, and differential diagnosis of true infarcts of the placenta

Hemodynamics at Rest and During Exercise in Normal Pregnancy as Studied by Cardiac Catheterization 12

“…This hypothesis is supported by the physiological observations of Barcroft, Her-kel, Hill, Flexner, McCarthy, and McClurkin (38,39) who found that uterine vein oxygen content in the rabbit is relatively elevated until the 18th to 20th day of gestation (comparable to the 7th to 8th month in the human female) after which there is a reduction in uterine vein oxygen content. Morphological studies of the placenta not only have demonstrated A-V shunt-like apparatus (40,41) but have also indicated that in the last weeks of gestation progressive senescence occurs, with obliteration of portions of the maternal placental circulation (42). Further evidence for aging of the placenta is found in studies of placental tissue respiration which have demonstrated a fall in the oxygen utilization by the placenta in the last month of gestation (43).…”

The Foetal Placental Circulation

“…The absence of foetal vessels which might be concerned in the nutrition of the placenta has been mentioned. This finding has been commented on by Zeek and Assali (1952) who wonder if the placenta is nourished by the maternal circulation. Spanner described an arrangement about the main vessels resembling vasa vasorum, and indeed in the present placental preparations small vessels can be seen arising from the main vessels.…”