Analysis of DNA fragmentation of in vitro cultured XXXX blastocysts using TUNEL.

@entity291 @entity1977 @entity28975 @entity39
Programmed cell death (apoptosis) characteristically affects the single cells of blastocysts whereas @entity39 affects cluster of cells in both the inner cell mass (ICM) and the trophectoderm (TE). This study uses the @entity28975 ( @entity28975 ) mediated @entity1977 nick-end labeling (TUNEL) assay as a way of evaluating the proportion of apoptotic cells and, thus, @entity291 blastocyst quality during in vitro culture at Days 6,7, and 8. Furthermore, parthenogenetic blastocysts were compared to in vitro fertilized blastocysts at Day 7. Confocal microscopy was used to generate three-dimensional reconstructions of the blastocysts. Apoptosis was observed in both early (Day 6) and late (Day 8) developing blastocysts. The dead cell index (DCI, total number of apoptotic nuclei/total number of nuclei) tend to increase as the in vitro culture time increases, and apoptosis is proportionately higher in the ICM than in the TE. The ratio of ICM to TE cells remains relatively constant even as the blastocysts cell number increases (Day 6 = 11.9 +/- 2.2, Day 7 = 11.2 +/- 0.5, Day 8 = 11.7 +/- 0.4). The overall cell number is significantly reduced in parthenogenetic blastocysts compared to Day 7 in vitro produced blastocysts (P = 0.037). The parthenogenetic blastocysts also show an increase of apoptosis over Day 7 controls. The decrease in cell number in the parthenogenetic blastocysts may be due to the increase of apoptotic nuclei observed. Based on these results we found the TUNEL assay to be a useful method for evaluating in vitro culture conditions of pre-implantation @entity291 embryos.
