Fig. 4. Mosaic analysis of the fates of specific blastomeres bearing foxa MASO. L. variegatus eggs were injected with foxa MASO and co-injected with rhodamine dextran as a dye tracer. Control donor embryos were injected with rhodamine dextran alone. At the 60-cell stage, two injected cells from each tier were transplanted to host embryos as indicated on the left diagrams. (Top row) Cells of the `an2' tier normally form ectoderm and foxa MASO-injected cells behaved like controls. (Second row) veg1 cells normally contribute to hindgut, midgut and vegetal ectoderm, and the foxa MASO-injected veg1 cells also contributed to gut and ectoderm. (Third row) veg2 cells normally contribute to foregut, midgut and SMCs. The foxa MASO cells contributed almost exclusively to SMCs. The red arrowhead points to the gut in both control and experimental embryos. (Bottom row) foxa MASO and control micromeres became normal PMCs.