Expression of StAR mRNA. A. Semi quantitative RT-PCR analysis (using GAPDH as an internal control) of StAR mRNA in +/+ (black bars) and -/- (hatched bars) ovaries at 0.5, 1.5, 2.5 and 3.5 day post coitum (d.p.c.). upper panel, inverse picture of ethidium bromide stained agarose gel shows a typical RT-PCR reaction; lower panel, bars, means ± SEM of the densitometric analysis. B. In situ hybridization of StAR in ovarian sections at 2.5 d.p.c. of PRLR+/+ and PRLR-/- mice. The predominant source of StAR expression is within cells of corpora lutea. A representative section is shown.