The use of fluorescein isothiocyanate (FITC) as a short-term cell lineage marker in the peri-implantation mouse embryo.

Fluorescein isothiocyanate (FITC) may prove to be a useful short-term cell lineage marker in the early mouse embryo. Blastomeres and embryos are labelled by a 10 min exposure to 0.5 mg/ml FITC in ungassed medium 16 containing 2 mg/ml polyvinylpyrrolidone. FITC-labelled embryos divide at rates comparable with control non-labelled embryos, undergo polarization and cell flattening at compaction at the 8-cell stage, generate distinct inner and outer cell populations at the 16-cell stage and form blastocysts with both ICM and trophectodermal tissues. The label is equally transmitted to all progeny of a labelled cell, is stable in the cells for several days and is not transferred to neighboring non-labelled cells via gap junctions. The fluorescent labelling observed is predominantly cytoplasmic and may reflect an unusual permeability of embryonic plasma membranes.