Surface antigen in early differentiation.

Abstract

Addition of Fab fragments from rabbit antiserum to surface antigen F9 to 2-cell stage mouse embryos in culture did not alter cleavage; however, the addition prevented the formation of compact morulae and blastocysts. A similar effect was observed when Fab fragments were added to already compact 8-cell stage or even older morulae, but disappeared at the beginning of blastocoel formation. This effect was reversible: uncompact 30-cell embryos washed free of Fab became compact in a few hours, produced blastocysts and upon reimplantation into pseudopregnant mothers can produce mice. Development was not altered by divalent anti-F9 antibodies, by Fab fragments from sera directed against other embryo surface antigens or by succinyl concanavalin A.