Immunohistochemical location of proteins related to pregnancy-specific beta 1-glycoprotein (SP1) and placental tissue proteins (PP5, PP8, PP9, PP10, PP11, PP12) in the afterbirth of Cynomolgus monkeys (Macaca fascicularis).

The occurrence and location of proteins antigenically related to human pregnancy specific beta 1-glycoprotein (SP1) and to human placental tissue proteins (PP5, PP8, PP9, PP10, PP11, PP12) were studied in the afterbirth (placenta, membranes, decidua, and umbilical cord) of cynomolgus monkeys with use of an immunoglobulin enzyme bridge (PAP) technique. The results were basically the same throughout pregnancy. The syncytiotrophoblast of villi showed clear positive stainings for SP1, PP8, PP9, and PP11, whereas the cytotrophoblast (villi) was found to show clear positive staining for PP9 only. The main sources of proteins related to SP1, PP9, and PP11 were the syncytiotrophoblast cells of the villi and PP8, the syncytiotrophoblast cells of villi as well as the chorionic trophoblast cells. PP12 was mainly located in histiocytes found in the decidua, umbilical cord, amnion, and chorion. There were only traces of PP5 and PP10 in the placentae of cynomolgus monkeys throughout gestation. As in human placentae some granulocyte-like blood cells in the intervillous space were strongly positive for PP8, PP10, and PP12. The findings in the afterbirth of cynomolgus monkeys were similar to those in the human; the monkey could thus serve as a model for the investigation of the new placental proteins.