The effects of the placenta and fetal fluids on the acceptance of foster young

Abstract

Maternal acceptance of foster young was altered by the interaction of the type of delivery of the rat pup and the presence or absence of placenta or liver. The presence of tissues which the mother ate did not alter the survival among normally delivered pups, but decreased survival among surgically delivered pups. Injecting the mothers with homogenates of these tissues indicated that eating of the placenta or liver by the mother was not essential for the effects. A 3rd experiment simulated normal and surgical delivery by washing surgically delivered animals with saline and smearing normally delivered animals with amniotic fluids, respectively. The data from this experiment showed that survival of the young was determined by the presence or absence of amniotic fluids on the pup interacting with the presence or absence of some material present in the placenta and liver.