PLATELET ENDOTHELIAL-CELL ADHESION MOLECULE-1 EXPRESSION DURING MOUSEPOSTIMPLANTATION DEVELOPMENT

With the aim to analyze the ontogeny of the mouse endothelium, monoclo nal antibody (mAb) MEC 13.3 was used for the immunohistochemical stain ing of frozen sections of different stages of mouse embryo development . This mAb specifically recognizes membrane reinforcement of endotheli al cells (EC) from mouse blood vessels, indicating the expression of a molecule related to the murine form of PECAM-1/CD31. The present stud y reports the expression of the murine PECAM-1/CD31 antigen, observed with the peroxidase-antiperoxidase technique, in a single cell type, w ith a typical non-differentiated morphology at an early stage of mouse postimplantation embryos. A progressive increase in the number of thi s cell type was observed in the early stages of murine development, bu t few were detected at mature stages. On the other hand, EC in days 9. 5, 14.5 and 19.5 postcoitum embryos were also recognized by the same m Ab MEC 13.3 allowing the recognition of a cell type related directly o r indirectly to vascular network development.