Influences of low doses of radiation on formation and differentiation of the cerebral cortex, (11)

Immediately after CF No. 1 Mice in the 13th or 15th day of gestation were exposed to 25R or 100R, 3H-thymidine was administered. Their 4-week-old offspring were autopsied and autoradiograms of their cerebrums were made. The distribution of the nerve cells (heavily labelled with 3H-thymidine) of the new cortexes at the vertex and architecture of the cerebrums were studied. The nerve cells of the offspring in the group exposed to radiation on the 13th day of gestation tended to exist in an area deeper than the 6th layer of the cerebral cortex, compared with those of the offspring in the control group. The nerve cells of the offspring in the group exposed to radiation on the 15th day of gestation tended to exist in more superficial layers (in the 2nd and 3rd layers), compared with those of the offspring in the control group. (Namekawa, K.)