Expression of Rat Prolactin-Like Protein B in Deciduoma of Pseudopregnant Rat and in Decidua During Early Pregnancy*

The rat PRL-like protein-B (rPLP-B) complementary DNA (cDNA), originally cloned from a late term placental library, hybridizes to transcripts in the deciduoma tissue artificially produced in pseudopregnant rats. The expression of rPLP-B in deciduoma is first observed 48 h (pseudopregnancy day 7) after the deciduogenic stimulus and increases to a maximum by 96-120 h (pseudopregnancy day 9-10). In situ hybridization studies show that rPLP-B hybridizes specifically to the antimesometrial cells of deciduoma tissue in day 9 pseudopregnant rats and to the homologous cells of the decidua that surround the embryo-trophoblastic structure at day 9 of pregnancy. A temporal study on the expression of rPLP-B during pregnancy shows that rPLP-B is concomitantly expressed by the decidual cells of maternal origin and the cytotrophoblast of fetal origin around day 13 of pregnancy.