SOME EFFECTS OF IMMUNOLOGICAL FACTORS ON GESTATION IN MICE

Abstract

Some effects of antigenlc dissimilarity of mother and conceptus on placental and fetal growth, and on gestation period were investigated. Mothers were immunized against or rendered tolerant to the foreign antigens of the hybrid fetus. Placentae and fetuses were weighed from the 12th day of pregnancy up to immediately before term. Some of the litters were allowed to come to term and recordings were made of the birth weights and the length of the gestation period. The results indicate that immunological factors have a significant effect on the size of the placenta and on the growth rate of the fetus. Probably because of this the period of gestation was altered. It was concluded that a unique balance is struck between the transfer area of the placenta and the mass of fetal tissue, to the detriment of the fetus if the placenta is unduly small, but to its advantage if a larger placenta is formed.