Interaction of genotype and fostering in the development of behavior of DBA and C57 mice.

Effects of fostering on behavior were studied in DBA/1Bg and C57BL/10Bg mice. Two-day-old pups were either infostered to mothers of their own strain, crossfostered to mothers of the other strain, or left as controls with their own mothers. Body weight, latency of emergence into an open field, open-field activity, defecation in an open field, spontaneous alternation, passive avoidance learning, and active escape learning were measured when the mice were 22 and 43 days old. Strain differences were observed for each trait except for spontaneous alternation. Fostering per se affected open-field activity and active escape learning. Similar effects of fostering per se on aggressive behavior have been reported by others. These may involve a role of ovarian cytoplasm, X-chromosomal genes, or uterine environment.