Regulation of uterine and conceptus secretory activity in the pig

Evidence is presented for the involvement of a number of specific uterineand conceptus-derived proteins in endometrial differentiation and conceptus or feml development. These secretory proteins include mitogens (insulin-like growth factor-I and -II, epidermal growth factor, uterine lumina] fluid mitogen). binding and transport proteins (uteroferrin, insulin-like growth factor and retinal binding proteins, respectively), protease inhibitors (antileukoproteinase. plasmin/trypsin inhibitor), and trophoblastic specific proteins. Using immunological reagents and specific complementary DNA (cDNA) probes, the tissue origins of several of these proteins have now been identified. In addition, the temporal regulation of messenger RNA (mRNA) production for a number of these proteins has been elucidated. The results suggest that althounh circulating and locally produced steroid hormones may be involved in regulating the synthetic abilities of these tissues during pregnancy, other, as yet undefined, factors may also mediate these activities.