Platelet-derived growth factor-receptor-beta in pig and cattle blastocysts

Presence and localization of the platelet-derived growth factor-receptor-beta (PDGF-Rbeta) was investigated in preimplantation bovine and porcine embryos. Blastocyst stages before and at the time of elongation were chosen, i.e. 9- to 13-day-old pig blastocysts and 14- to 16-day-old cattle blastocysts. Immunohistochemistry was carried out with monoclonal antibodies directed against the beta-chain of the PDGF receptor. Staining was examined by light microscopy. PDGF-Rbeta was found in all cell types of the investigated stages in both species. Staining was mainly cytoplasmatically with cell membranes most likely being positive as well. Staining was very constant in all the stages and cell types investigated, except for mesoderm cells and for trophoblast cells adjacent to the embryoblast in some pig embryos. Because PDGF-Rbeta is almost constitutively expressed in all cell types of bovine and porcine blastocysts, it is likely that PDGF participates in cellular differentiation and blastocyst elongation preceding implantation in these species.