ABNORMAL FETAL DEVELOPMENT IN THE MARMOSET (CALLITHRIX JACCHUS)

Perinatal mortality and the frequency of fetal abnormalities is greater in human multiple pregnancies than it is in single pregnancies (Bulmer, 1970). Multiple births are a regular feature of reproduction in non-human primates of the genus Callithrix, twins being the normal number of young although one or three may sometimes be born (Napier & Napier, 1967). Hill (1969) has pointed out that marmosets (Callithrix jacchus) kept in captivity may suffer a variety of obstetrical mishaps, particularly dystocia. The present account is of an abnormal pregnancy, of a type not previously reported for a non-human primate, in a marmoset. The animal was part of a colony of imported marmosets maintained at the Medical Research Council Laboratory Animals Centre, Carshalton. The pregnancy was the first for this animal in captivity and was uneventful until the onset of labour. Due to the subsequent obstetrical problem of obstructed delivery, a Caesarean section was performed without premedication under halothane anaesthesia. A full term fetus (Embryo A), with head located in the cervix uteri, and a singl