Proopiomelanocortin, prolactin and growth hormone messenger ribonucleic acid levels in the fetal sheep pituitary during late gestation.

We have measured the relative levels of proopiomelanocortin (POMC), prolactin (PRL) and growth hormone (GH) messenger ribonucleic acid (mRNA) in the anterior and neurointermediate lobes of the fetal pituitary during the last 1-3 weeks of gestation. The mean POMC mRNA/18S RNA ratio in the fetal anterior pituitary was significantly greater (p<0.01) at 130-136 days (0.90±0.08; N=9) than at 141-143 days of gestation (0.67±0.07; N=6). In contrast, the mean PRL mRNA/18S RNA ratio increased significantly (p<0.01) between 130 and 13 6 days (0.31±0.05; N=9) when compared with 141-143 days of gestation (0.58±0.10; N=6)