The in vivo fertilized in vitro grown embryos examined for apoptosis and necrosis. (A) A day five in vitro cultured embryo arrested at six-cell stage from the control group is observed before and after epifluorescent technique. Green fluorescence by Annexin V is observed over the outer cell membrane and means that apoptosis is underway. There is negative PI fluorescence at the time of harvest. (B) An arrested embryo at the morula stage becomes severely fragmented. Green fluorescence can be noted following Annexin V staining with simultaneous red fluroscence by PI staining. (C) A blastocyst cultured from the control group appears to be normal looking prior to epifluorescent observation. The same blastocyst under epifluorescent microscope shows apoptotic changes with Annexin V fluorescence and absence of PI fluorescence. (D) An apoptotic blastocyst, following Annexin V and PI staining, revealed green fluorescence. Under epifluoresvent microscope, Annexin V staining revealed a well fluorescent membrance with central clearing.
Lin et al. BMC Cell Biology 2003 4:14 doi:10.1186/1471-2121-4-14