The cell content and proliferative response of the rat thymus during first syngeneic and allogeneic pregnancy, and the effects of strain difference.

Two hundred female rats, 91-101 days of age, were used in this investigation which provided data on cell content and proliferative response of the thymus. The observations began in oestrous phase virgin females from two highly inbred strains AO(RT1u/AgB2) and DA(RT1a/AgB4), continued at five day intervals throughout syngeneic and allogeneic pregnancy in both strains and were completed in the immediate post-partum period. This experimental protocol permitted sequential observations throughout gestation and allowed syngeneic: allogeneic and interstrain comparisons to be made. The syngeneic: allogeneic comparisons demonstrated significant differences in the thymic proliferative responses while the AO:DA comparisons demonstrated significant differences in the thymic cell contents.