THE STAGE-SPECIFIC EXPRESSION OF TEC-1,TEC-2,TEC-3, AND TEC-4 ANTIGENS ON BOVINE PREIMPLANTATION EMBRYOS

The preimplantation developmental period is associated with constant c hanges within the embryo, and some of these changes are apparent on th e embryo cell surface. For example, during transition from maternal to embryonic genome control and the compaction and differentiation of em bryonic cells, the cell surface undergoes morphologic alterations that reflect changes in gene control. In order to gain insight into the ev ents occurring during embryonic development and cellular differentiati on, monoclonal antibodies specific for cell surface antigens (TEC anti gens) of embryonic cells have been generated previously and shown to r ecognise either the carbohydrate moiety of embryoglycan or a developme ntally regulated protein epitope. The TEC antigens have been identifie d on mouse preimplantation embryos, and their expression is specific t o particular developmental stages. To determine whether these antigens are conserved in higher mammals, we examined the expression of four T EC antigens (TEC-1 to TEC-4) on in vitro-derived bovine and murine emb ryos during the preimplantation stage of development, It was found tha t bovine oocytes and embryos derived from in vitro maturation (IVM) an d in vitro fertilisation (IVF) showed stage-specific expression of eac h of the TEC antigens investigated, with the pattern of expression ove rlapping but not identical to that seen in the mouse. Immunoprecipitat ion together with Western blot analysis showed that the TEC monoclonal antibodies recognised a single glycoprotein band with an apparent mol ecular weight of 70 kDa. Confocal microscopy of immunofluorescence sta ining of the bovine cells showed this protein to be located on the cel l surface. The apparent negative expression of these TEC antigens by i mmunohistochemistry and immunoprecipitation at particular stages of de velopment appears to be due to the epitopes being inaccessible to the TEC antibodies, since Western blotting revealed the TEC antigens to be present at all stages of development examined. Antibodies identifying stage-specific antigens will provide useful markers to characterise e arly embryonic cells, monitor normal embryonic development in vitro, a nd identify cell surface structures having a function in cell-cell int eractions during embryogenesis and differentiation. (C) 1998 Wiley-Lis s, Inc.