Early development in mice. VI: Additive and interactive effects of offspring genotype and maternal environments.

Ovarian transplantation (OT) and fostering (F) methods were used concomitantly to test for genotype effects and cytoplasmic, uterine and postnatal maternal effects on nine sensori-motor responses employed for measuring development in two inbred stains of mice: NZB (N) and CBA/H (H). Parental strain differences were observed for six responses: forelimb placing, hindlimb placing, visual placing, crossed extensor, vibrissae placing and bar holding. Reciprocal F1 comparison alone indicates a single H vs. N global maternal effect (visual placing), whereas the joint use of the OT and F methods shows a parental vs. F1 global maternal effect on parental pups for three responses (hindlimb placing, grasping and visual placing) and on F1 pups for two responses (forelimb placing and visual placing). Moreover, a postnatal maternal effect is reported for five responses; righting, forelimb placing, grasping, crossed extensor and visual placing. The effect of the maternal genotype via the uterine environment is observed for four responses: righting, fore- and hindlimb placing and visual placing. Genotypic effects are also demonstrated on fore-and hindlimb placing, bar holding and visual placing. These results confirm the absence of a general genetic factor and demonstrate the absence of a general environmental factor the rate of the early sensori-motor development.