Abstract
Perinatal changes of the gastric parietal cells were studied under normal and various experimental conditions. Histologic examination revealed that the parietal cells appeared markedly increased in number from late fetal to early neonatal days. When premature newborn rats were delivered by cesarean section and were nursed by foster mothers for 1 or 2 days, the degree of increase of these cells reached nearly that in the normal neonates. On the other hand, in fetuses retained in utero 1 day beyond the normal gestation, these cells appeared not increased in number. When these postmature fetuses were delivered, the parietal cells turned to increase in number in a degree similar to that in the normal neonates. Milk given to the premature newborn rats caused 6 h later a marked increase in the number of the parietal cells. Milk given to fetuses in utero also caused an increase of these cells. The results suggest that the development of the parietal cells in perinatal rats is accelerated by the intake of milk and that the fetal parietal cells are ready to respond to milk given at least 1 day before birth.