Genetic and uterine effects on survival in mice selected for body weight.

Intraand inter-line transfers of blastocysts were performed between two lines of mice selected for high (H6) and low (L6) body weight at 6 weeks of age. A greater percentage of L6 blastocysts survived to term than did H6 blastocysts (7\m=.\8%,P < 0\m=.\01)and more L6 recipients littered than did the H6 recipients (19\m=.\7%,P < 0\m=.\01).A greater percentage of the mice born to the L6 recipients was found alive at birth (8\m=.\5%,P < 0\m=.\05),as was a greater percentage of the young carried in the uteri of the opposite line (8\m=.\3%,P < 0\m=.\05).