Fig. 1.

Serum progesterone concentrations and differential gene expression in corpora lutea (CL) collected on days 12 and 14 of pregnancy (P) and the estrous cycle (NP). Serum progesterone was maintained from day 12 to 15 of pregnancy, whereas it declined in a manner consistent with luteolysis from day 12 to 15 of the estrous cycle. Number of genes differentially expressed (>1.5-fold, P < 0.05) was determined via microarray and is shown in context of serum progesterone profiles as a function of day or pregnancy status. *Significant difference (P < 0.05) between serum progesterone from nonpregnant and pregnant ewes on day 15. Values represent means.