Ultrastructural analysis of mitochondria in pre-implantation embryos.

Mitochondria morphology was analyzed in early (2- and 4-cell) and later stage (morula) SCNT and ICSI embryos. Round and elongated mitochondria were counted per section (nuclear or perinuclear region) of a single blastomere (2–3 blastomeres per embryo, n = 3; 3000X). Numbers are mean (± standard deviation) of analyzed areas. Mitochondrial cristae morphology (developed, medium developed and undeveloped; see also Figure 2) was characterized to define level of mitochondrial maturation.