Comparison of the expression of specific cell surface epitopes on in vitrofertilized and parthenogenetic bovine embryos

Parthenogenetic embryos, which are produced by the spontaneous or artificia l stimulation of the oocyte, partially develop in the complete absence of t he male gamete but fail to produce live young in many mammalian species. Th e identification of developmentally regulated molecules on the cell surface of embryos has implicated their possible role in cell interactions during embryogenesis and differentiation. In this study the expression patterns of four stage-specific cell surface antigenic determinants (TEC-1, -2, -3, an d -4) were investigated in both parthenogenetic and in vitro fertilized bov ine embryos. When compared to embryos produced using in vitro fertilization methods the parthenogenotes, although appearing morphologically normal, di ffered markedly in their TEC epitope pattern of presentation. TEC-1, -2, -3 , and -4 epitope presentation on in vitro fertilized embryos occurred durin g specific stages of preimplantation development. TEC-1 and -2 presentation was detected on oocytes and blastocysts only, TEC-3 on morulae and blastoc ysts, and TEC-4 on oocytes through to 8-cell embryos, with all subsequent s tages negative. Parthenogenetic embryos did not show TEC-1, -2, or -3 epito pe presentation whereas the TEC-4 epitope was present throughout the develo pmental period examined. Enzymatic cleavage of sialic acid residues on in v itro fertilized and parthenogenetic embryos resulted in presentation of the TEC epitopes during all the embryonic stages. Western blot analysis of the embryos showed the TEC epitopes to be present on all the embryonic stages examined. This study suggests the mechanisms responsible for control and pr esentation of each of the TEC epitopes may not; be functioning the same in parthenogenetic embryos that undergo changed glycosylation or deglycosylati on resulting in altered patterns of sialylation. The study also shows TEC e pitope presentation may prove to be a useful indicator of parthenogenetical ly activated bovine embryos. J. Exp. Zool. 284:392-400, 1999. (C) 1999 Wile y-Liss, Inc.