It has been observed that apoptosis occurs in @entity1 blastocysts. In other types of cell, the characteristic morphological changes seen in apoptotic cells are executed by caspases, which are regulated by the @entity588 family of proteins. This study investigated whether these components of the apoptotic cascade are present throughout @entity1 preimplantation development. Developing and arrested two pronucleate embryos at all stages were incubated with a fluorescently tagged caspase inhibitor that binds only to active caspases, fixed, counterstained with @entity14939 ( @entity14939 ) to assess nuclear morphology and examined using confocal microscopy. Active caspases were detected only after compaction, at the morula and blastocyst stages, and were frequently associated with apoptotic nuclei. Occasional labelling was seen in arrested embryos. Expression of proapoptotic @entity589 and @entity1835 and anti-apoptotic @entity588 was examined in single embryos using RT-PCR and immunohistochemistry. @entity589 and @entity588 mRNAs were expressed throughout development, whereas @entity1835 mRNA was expressed mainly after compaction. Simultaneous expression of @entity589 and @entity588 proteins within individual embryos was confirmed using immunohistochemistry. The onset of caspase activity and @entity1835 expression after compaction correlates with the previously reported appearance of apoptotic nuclei. As in other types of cell, @entity1 embryos express common molecular components of the apoptotic cascade, although apoptosis appears to be suppressed before compaction and differentiation.

Caspase activity and expression of cell death genes during development of XXXX preimplantation embryos.

@entity1 :: ('9606', 'Species') :: ['human'] @entity589 :: ('581', 'Gene') :: ['BAX'] @entity588 :: ('596', 'Gene') :: ['BCL-2'] @entity14939 :: ('MESH:C007293', 'Chemical') :: ['DAPI', '4,6-diamidino-2-phenylindole'] @entity1835 :: ('572', 'Gene') :: ['BAD']
@entity1 :: (9606,Species) :: ['human']
