Figure 3.

Hypothesis concerning the expression profile ofsome differentially expressed genes Our previous results suggest that Cyp21a1 is expressed at different precise gestation time on GD 15 for each gender [27] as shown in the present figure. This hypothesis would explain why the expression profile of Cyp21a1 on GD15.5 varied from litter to litter and presented one of the following patterns : 1) high expression in female fetal lungs only; 2) high expression in male fetal lungs only; or 3) no elevated expression in male and female fetal lungs. Because Balb/C is an inbred strain, the mating window of 16h would explain the variation between litters. Genes presenting such an expression profile cannot be studied by microarrays from a pool of many litters because the sex difference in expression could be lost.