The expression of surface antigens on three trophoblastic tissues in the mouse.

The expression of paternal and maternal antigens on three types of mouse trophoblast cultured in vitro has been examined with the mixed haemadsorption test. Primary trophoblastic giant cells outgrown from blastocysts and placental trophoblast from 16-day pregnancies expressed antigens of both sources at all stages in culture. Secondary trophoblastic giant cells outgrown from the tip of 8-day ectoplacental cones did not give a positive reaction until they had outgrown for 3-5 days. Microdensitometry after Feulgen staining showed that the cells which gave a positive mixed haemadsorption response were polyploid. Incubation of blastocysts and ectoplacental cone tissue with progesterone, oestradiol-17beta and hCG did not affect the results.