Examples of morphological stage grading used in this study. Putative zygotes were cultured until day 5, when embryos were examined for evidence of compaction. Embryos that showed compaction by this time were classified as compacted morula (A) while embryos that did not exhibited compaction or attained 16-32 cells were classified as "early degenerative" (B). Compacted morulas were further cultured until day 8 when they were evaluated for presence of blastocoele. Embryos that showed distinct inner cell mass and blastocoele were classified as "blastocysts" (C) and embryos that did not properly complete transition from morula to blastocyst were classified as "late degenerative" (D). Transcriptomic profiles of blastocysts (C) and late degenerative embryos (D) were compared in this study.
Huang et al. BMC Genomics 2010 11:23 doi:10.1186/1471-2164-11-23