Distribution of p21rasin postimplantation rat embryos

摘要

AbstractExpression ofrascellular oncogenes during the early postimplantation period in the rat was investigated using immunohistochemistry to p21raswas used in an indirect avidin‐biotin‐peroxidase (ABC) technique. Positive staining indicating the presence of p21raswas found in embryos from 6.5 to 12 days embryonic age. In early egg cylinders (6.5 days), positive staining for p21raswas observed on the ectoplacental cone, primitive ectoderm and trophectoderm, while primitive endoderm and parietal endoderm appeared paler. In later egg cylinder stages (7.5 days), strong positive staining was observed in the primitive embryonic ectoderm and ectoplacental cone, but parietal and visceral endoderm still appeared to be devoid of positive staining. As development proceeded during primitive streak stages, the visceral and parietal endoderm became positively stained. By 10 days, all tissues appeared to be positive for p21ras, with strong staining appearing in the heart and neural elements. Therefore, p21rasdoes not appear to be ubiquitous in the rat conceptus prior to gastrulation, but shows differential distribution, appearing later in endodermal derivatives. Possibly p21rasis involved in determination of the ectodermal and endodermal lineages.© Willey‐Lis