Quantitative comparison of prolactin production by decidua compacta and spongiosa from the first trimester elective termination of pregnancy.

Prolactin (PRL) producing capacity was studied in explants of decidua compacta and decidua spongiosa obtained from 41 patients undergoing termination of pregnancy at gestation 6 to 12 weeks. In vitro PRL producing capacity, expressed as mIU/g protein, of the decidua compacta was significantly higher (P < 0.05) than those of decidua spongiosa. Production of PRL increased with gestation from 6 to 12 weeks with a more rapid rate at the later gestation. The pattern of increase fitted significantly (P < 0.0001) to the exponential model for both decidua compacta and decidua spongiosa. The exponential regression equations for decidua compacta and decidua spongiosa were (ln y = 4.25 + 0.19x) and (ln y = 2.80 + 0.31x) respectively. Hence, although both decidua compacta and decidua spongiosa had a similar pattern of increase in PRL production, the rate of increment was significantly greater in decidua spongiosa than in decidua compacta. These findings suggest that separating decidua compacta and decidua spongiosa of the first trimester would reduce the heterogeneity of decidual tissue and offer a new approach to the studies of the synthesis, release and regulation of PRL production by human decidua.