Rhodamine 123 as a cytoplasmic stain for mammalian zygotes.

A mitochondrion-specific fluorescent dye, rhodamine 123, stains the cytoplasm of ova from mice, rabbits, sheep, cattle and pigs. Mouse zygotes stained with rhodamine 123 are often observed with areas of negative stain where the pronuclei are located. However, such areas of negative staining are not observed in zygotes from rabbits, sheep or cattle. In vitro viability of mouse zygotes stained with rhodamine 123 is high if observed with fluorescent microscopy for 5 min or less. Observation for more than 5 min results in a significant effect on embryo developmental potential in vitro.