Abstract
Investigation of the various factors which control the placental circulation has necessarily been limited owing to the experimental difficulties involved. It is suggested that the following technic may offer a line of approach to some of the problems involved.
Methods. The experimental animals used were cats or bitches which were in an advanced stage of pregnancy. Rabbits were found to be unsuitable owing to the friability of the placental vessels. Anesthesia was induced with open ether, and maintained with chloralose given intravenously in a dose of 100 mg/kilo body weight. Both vagi were cut, and the carotid blood pressure recorded by means of a mercury manometer. The abdomen was opened with as short an incision as was compatible with adequate access, and a part of the uterus containing one foetus brought up into the wound. A small cork platform approximately 5 cm square was approximated to the section of uterus exposed, and the uterine peritoneum loosely stitched to the two nearest corners of the platform with silk ligatures. An incision about 2 cm long was then made through a part of the uterine wall which was free of placental attachments, the membranes ruptured, and the hind-quarters of the foetus delivered until the umbilical cord came into view. If the foetus was lying in a favorable position, it was possible to expose the umbilicus with the umbilical vessels without delivering any part of the foetus. The umbilical cord was then ligatured in 2 places as close to the umbilicus as possible, divided, and the placental end delivered through the wound in the uterine wall. Thereafter the foetus was replaced within the uterus and the uterine wall stitched up again, leaving only the free end of the umbilical cord protruding.
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