Interaction between inoculated allogeneic lymphocytes and fetal rats.

Interaction between allogeneic lymphocytes and 12-20-day gestation rat fetuses was examined in vitro and in vivo. Intravenous injection of lymphocytes was achieved either by in vitro cannulation of the vitelline vein followed by culture of the whole fetus, or of its organs, or by in utero cannulation of the vitelline vein through the uterine wall. Cytotoxic reactions on the part of the inoculated allogeneic lymphocytes against fetal tissue could not be detected in the young hosts. The fetal spleen, mesentery and intestine appeared to have a specific affinity for adult lymphocytes from the earliest gestational age examined.