TABLE 1.

Timed pregnancy analysis of Prep1^i/i embryos^a

Embryonic stage	nb	No. of crosses	No. (%) of embryos or pups with genotype
			+/+	+/i	i/i
E14.5	200	15	52 (26)	104 (52)	44 (22)
E15.5-17.5	194	26	51 (25.4)	100 (50.5)	43 (21.4)
P0	221	34	73 (33.0)	132 (59.7)	14 (6.3), 2 (0.9)c

^aThe mice employed in these crosses had been backcrossed from 7 to 9 generations with wt C57BL/6.

^bNumbers of embryos or newborn pups analyzed.

^cTwo mice were born alive but died within the first day.