Two hundred and ten capillaries taken by punch biopsy at 2 to 5 hours of age from term, normal, newborn infants were examined by electron microscopy. Six infants had early cord clamping and five had late cord ligation. In the late-clamped group, the capillaries were more distended morphologically as shown by a smaller endothelial index (endothelial area/total capillary area). In comparison to the early-clamped group, the late-clamped infants also had a larger number of fenestrated small blood vessels. Since fenestration is an anatomical structure related to rapid fluid exchange, it is suggested that this finding is an indication of a more active fluid transudation from the intravascular to the extravascular compartment in the late-clamped infants in response to a greater circulatory volume deriving from placental blood transfusion at birth. It is also suggested that the large number of fenestrated vessels in the late-clamped infants is a result of an increased number of openings of arteriovenous communications.
- Copyright © 1968 by the American Academy of Pediatrics