Figure 5.

Deletion of Ipl promotes placental but not fetal growth in an Igf2-null background. (A) Placental and fetal weights of conceptuses with the indicated Ipl and Igf2 expression status, measured at 16.5 dpc. Deletion of Ipl partially rescues the placental growth retardation but does not rescue fetal growth in the Igf2 nulls. The horizontal and vertical bars indicate means and standard deviations. t tests for equivalence of the weight distributions are indicated. (B) Ratios of the area of the spongiotrophoblast to labyrinth (Spong/Lab) in midline sections of all Ipl⁺Igf2⁺ and Ipl⁻Igf2⁻ placentas obtained from pooling two crosses (16.5 dpc) carried out between the Ipl^neo and Igf2^lacZ lines. Although the Ipl⁻Igf2⁻ placentas are slightly smaller than the controls, they show an increased spongiotrophoblast/labyrinth ratio.