Fibroblast Growth Factor Receptor (FGFR)-1 and -2 in the Ovine Corpus Luteum throughout the Estrous Cycle

Fibroblast growth factors (FGFs) probably play an important role in development and maintenance of the vasculature of the corpus luteum (CL). The objective of the present study was to evaluate the distribution and levels of fibroblast growth factor receptors (FGFRs) in the ovine CL from the early, mid-and late stages of the estrous cycle. Presence of FGFR-1 and -2 receptors was evaluated in CL by using Western analysis, immunohistochemistry and topical autoradiography. Western analysis demonstrated that the levels of FGFR-1 and -2 were similar in the early and mid-cycle CL but increased (p < 0.05) in the late stage of the estrous cycle. Immunohistochemistry and topical autoradiography demonstrate that both parenchymal (steroidogenic) and nonparenchymal (e.g. endothelial, fibroblastic) cells express FGFR-1 and -2. FGFR-1 was localized to the luteal vasculature throughout the estrous cycle; in the parenchymal cells, it was present during mid-cycle but was barely detectable in the late stage. Conversely, FGFR-2 was present in the parenchymal cells at all stages of the estrous cycle but localized to the larger microvessels only at the late stage. These data demonstrate that FGF receptors are present in the parenchyma as well as the vasculature of the CL which suggests that FGF is involved in the regulation of luteal parenchymal and vascular function.