Abstract
BackgroundEmbryo implantation plays a major role in embryogenesis and the outcome of pregnancy. Plasminogen activators (PAs) have been implicated in mammalian fertilization, early stages of development and embryo implantation. As in-vitro developing embryos resulted in lower implantation rate than those developed in-vivo we assume that a reduced PAs activity may be involved.In the present work we studied the effect of EGF on PAs activity, quantity and embryo implantation.MethodsZygotes were flushed from rat oviducts on day one of pregnancy and grown in-vitro in R1ECM supplemented with EGF (10 ng/ml) and were grown up to the blastocyst stage. The control groups were grown in the same medium without EGF. The distribution and quantity of the PAs were examined using fluorescence immunohistochemistry followed by measurement of PAs activity using the chromogenic assay. Implantation rate was studied using the embryo donation model.ResultsPAs distribution in the embryos was the same in EGF treated and untreated embryos. Both PAs were localized in the blastocysts' trophectoderm, supporting the assumption that PAs play a role in the implantation process in rats.EGF increased the quantity of uPA at all stages studied but the 8-cell stage as compared with controls. The tissue type PA (tPA) content was unaffected except the 8-cell stage, which was increased. The activity of uPA increased gradually towards the blastocyst stage and more so due to the presence of EGF. The activity of tPA did not vary with the advancing developmental stages although it was also increased by EGF.The presence of EGF during the preimplantation development doubled the rate of implantation of the treated group as compared with controls.
Highlights
Embryo implantation plays a major role in embryogenesis and the outcome of pregnancy
The activity of type PA (tPA) did not vary with the advancing developmental stages it was increased by Epidermal Growth Factor (EGF)
The tip of the pipette was Immunolocalization of tPA and urokinase-type plasminogen activator (uPA) in preimplantation embryos; effect of EGF Immunohistochemical staining for the location of tPA and uPA in preimplantation embryos developed in-vitro with or without exogenous EGF are shown in figure 1
Summary
Embryo implantation plays a major role in embryogenesis and the outcome of pregnancy. Plasminogen activators (PAs) have been implicated in mammalian fertilization, early stages of development and embryo implantation. As in-vitro developing embryos resulted in lower implantation rate than those developed in-vivo we assume that a reduced PAs activity may be involved. In the present work we studied the effect of EGF on PAs activity, quantity and embryo implantation. The major obstacle in IVF treatments is the low embryo implantation rate. Plasminogen activators are members of one of the main enzyme family that participate in embryo implantation. Plasminogen activators (PAs) and matrix metalloproteinases (MMPs) have been implicated in mammalian gametogenesis [1], ovulation [2,3], fertilization [4,5], early development and embryo implantation [3,6,7]. Plasmin can degrade directly or indirectly, through the activation of metalloproteinase zymogens, all components of the extracellular matrix [8,9]
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