Immunoscanning electron microscopy of antigenic determinants of T/t-complex (tw18) mouse embryos

tw18 antigen(s) have been localized by immunoscanning electron microscopy in 7.5-day mutant embryos using a primary antiserum to tw18 made and defined on male germ cells and a secondary rabbit anti-mouse Ig antibody coupled to hemocyanin. Homozygotes (tw18/tw18) diagnosed on morphological grounds are more densely labeled primarily on those cell types affected by genetically caused dysfunction. Eight-celled tw18 embryos are not labeled. This finding of embryonic cell type specificity, together with the available evidence for stage specificity, implicate a function for t-antigens in embryonic development.