INSULIN-LIKE GROWTH-FACTORS AND BLASTOCYST DEVELOPMENT

The interactions between the maternal uterus and the developing conceptus that underlie normal blastocyst development and successful progression of pregnancy are complex. Recent studies implicate peptide growth factors in the initiation, establishment and maintenance of pregnancy and in maternal-embryonic communication. The insulin-like family of growth factors appear to function as key mediators of the coordinate development of the uterus and conceptus during early pregnancy by virtue of their ability to influence directly or indirectly, the synthesis and secretion of uterine and conceptus secretory proteins. The autocrine and paracrine modes of action of the insulin-like growth factors (IGFs) are modulated within the uterine microenvironment by Type I IGF receptors and IGF binding proteins (IGFBPs), which are themselves subject to local control within the uterus and conceptus, An understanding of the mechanisms by which IGFs regulate and are regulated by, the expression of conceptus signals for maternal recognition of pregnancy may provide novel insights and practical applications towards increasing reproductive efficiency in large animals.