Abstract
7S gamma 2 globulin was fractionated from the sera of rhesus (Macaca mulatta) monkeys by diethyl-aminoethyl cellulose column chromatography and labeled with 131I The labeled gamma globulin was injected into four rhesus monkeys during the last 4 weeks of gestation, and later recovered from the fetuses. Gamma globulin-131I was injected into two fetuses during the last 4 weeks of gestation, and later recovered from the maternal circulation. Gamma globulin-131I injected into three recently delivered lactating mothers was not recovered from their nursing infants. The results showed that during the last 4 weeks of gestation gamma globulin was transferable between mother and fetus, and passage was probably through the placenta. There was no transfer from lactating mothers totheir newborn offspring.