The data above suggest a role for IGF-I in development and decidualization of the uterine stroma. Our data suggest that the actions of IGF-I may be modified by IGFBP-4. Croze et al. proposed that in the rat uterus, IGFBP-1 may inhibit the mitogenic activity of IGF-I to allow for the differentiation of stromal tissue. In the mouse, IGFBP-4 could inhibit the mitogenic activity of IGF-I in certain endometrial stromal cells, thereby permitting decidualization to occur in certain uterine stromal cells at specific times. buy ortho tri-cyclen online
In summary, this study demonstrates that the presence of specific embryo factors is not required for IGF-I and IGFBP-4 expression in the periimplantation uterus. Before implantation, the maternal hormones of pregnancy can support IGF-I and IGFBP-4 mRNA expression in the uterus. Beyond gestational Day 4, decidualization of the uterine stroma can maintain the expression of these two genes. These studies suggest that the expression of IGF-I and IGFBP-4 mRNAs may be associated with decidualization of uterine stromal cells. However, further studies must be conducted in order to define the exact role(s) of IGF-I and IGFBP-4 in decidualization and to better understand the complex involvement of the IGF system in embryo growth and implantation.