ABSTRACT
The development of the corpus callosum of male Swiss mice was perturbed by exposure to gamma radiation at embryonic day 16 with total doses of 2 Gy (N = 48) or 3 Gy (N = 26). At adulthood paw preference was studied in these callosal defective animals and in 93 control nonirradiated male Swiss mice. The analysis of directional laterality indicated a populational tendency for right paw use in the 2 Gy group (60 per cent ) that was markedly increased in the 3 Gy group (95 per cent ). In the 3 Gy group, directional laterality was significantly different from chance in contrast to that observed in normal controls (49 per cent ). In the three groups most mice presented a significant individual paw preference. These data are consistent with our hypothesis that the early absence of the corpus callosum disrupts the normal pattern of directional asymmetries