English: Bull sperm, which was painted by fluorescent DNA-dye Hoechst 33342, were three times washed (ie centrifugation, resuspended in medium without dye Hoechst 33342) and then added unpainted cells (pictured left, unpainted cells are dark, not illuminated). After 1.5 hours incubation of the mix, all cells began to fluoresce, there was redistribution of Hoechst 33342 dye (photo right). Mammalian spermatozoa have membrane pumps (ABC efflux pump), which can to pump the dye into outside. Whether is it an active process, or passive diffusion? Experiments continue.

English: Hoechst 33342 redistribution