TRANSFER OF ⁸⁵SR THROUGH PLACENTA AND MOTHER'S MILK I

Abstract

The transfer of "Sr from mother to offspring througFn the placenta during intra-uterine life arnd through mothers milk during nursing was observed in experimentalmice.Three groups of female mice were injected intraperitoneally with 2, uni of "Sr ixr0-5 ml salune solution as a single tracer dose atnd mated at differ"ent intervals after injection.The amounts of"Sr accumulated in the youmng at birth were 0.087, 0.067, and 0.047per cent or the ctose in those derived trorn mice mated t -2 weeks, 2 -3 weeks, ana 4-5weeks after "Sr unjectiort, respectively. From these results, it was apparent that tlaeshorter the interval betvveen injection and parturition, the greater became the "Sr con-tent in the young at birth.In the young brought forth by an "Sr-contamiuaa-ted mother and nursed with herbreast rnulk, the accumulation of "Sr increased rapidly on the 3rd day after birth. The"St retained by the suckling was derived partially frorn placental transfer and partially1f0rT1 mothers milk. Thorn relative contributions by the transplacental and milk-borne"81 taken by the suckling during the nursing period were calculated. The contributionof transplacental "Sr decreased rapidly after birth. On the contrary, that of milk-borne"Sr increased during nursing.