QPCR analysis of (A) oPRP1 and (B) oPRP2 mRNA in ovine placenta. Total sheep RNA was extracted from PTM and ICOT on Day 45 (early), Day 95 (middle) and Day 135 (late) of gestation. Expression of these mRNAs was normalized to the expression of GAPDH measured in the corresponding RNA preparation. Values are means ± SEM. Values with different letters (a, b, c and d) are significantly different (P < 0.05).