Experiments on the maternal-foetal barrier in the mouse. II. A test for the transmission of maternal serum albumin into the foetal circulation following x-irradiation.

LENGEROVA (1957) obtained indirect evidence that placental permeability to transplantation antigens could be induced in the rat by delivering 200 r. of X-irradiation to the pregnant uterus on the 15th day of gestation. The young were found subsequently to be immunologically tolerant of grafts of maternal skin. The passage of transplantation antigens into the foetus in sufficient quantity to induce tolerance strongly suggests transplacental leakage of leucocytes (since erythrocytes are ineffective in inducing tolerance to grafted skin). Finegold & Michie (1961) made a direct test for mother-to-foetus transmission of labelled erythrocytes in the mouse following X-irradiation at various stages of pregnancy, but obtained negative results. In order to characterize further the limits to permeation from mother to foetus, we have tested for the transmission, both with and without X-ray treatment, of albumin-bound Evans blue and of any free dye which may, under the conditions employed, be present in the circulation of the mother.