Responses of foetal and new‐born monkeys to asphyxia

Many clinical studies have implicated anoxia before or during birth as a cause of later neurological defects.This is thought to be one of the principal causes of human cerebral palsy and mental retardation, but few efforts have been made to apply laboratory techniques to a solution of the problem (Bailey, 1958).Studies of asphyxia neonatorum in foetal guineapigs have been correlated with histological changes in the nervous system (Windle & Becker, 1942, 1943; Windle, Becker & Weil, 1944; Windle, 1958; Bailey & Windle, 1959).Other laboratory species have been used to investigate effects of oxygen deprivation after birth (Ford, 1928; Fazekas, Alexander & Himwich, 1941; Meier & Bunch, 1950; Meier & Menzel, 1955) but without adequate anatomical controls.Yet the' differences betwe'en human foetuses or new-born infants and these laboratory animals'have been considered too great to permit close comparisons to be drawn.The primate should be a more favourable subject, and we have employed the rhesus monkey, Macaca mulatta, which has much in common with man in respect to the physiology of reproduction, although its gestation period is shorter (168 days, on the average; van Wagenen, 1958) and the offspring is more advanced in development at birth.METHODS Rhesus monkeys were provided from caged colonies.They were mated during one 24-hr period of the menstrual cycle.The maintenance of caged breeding colonies, the practice employed to obtain timed matings, and the procedures used in rearing asphyxiated and normal infants in a nursery have already been described (Jacobson & Windle, 1960).Foetuses were delivered, without rupturing the foetal membranes, by Caesarean section under local anaesthesia at 159 + 2 days of gestation.The foetus was asphyxiated by leaving it within the membranes for a variable interval of time after the last gasp.After it had been removed from the membranes, an airway was established by tracheal intubation through a neck incision in the first four experiments, but this was discontinued in favour of end&.29-2