FIG. 3.
Distribution of mitochondria in 2-cell embryos with altered pHi. These confocal micrographs of 2-cell embryos show how altering pHi disrupts the perinuclear organization of mitochondria. The embryos were cultured in either HECM-10 (A, D), HTMA (B, E), or HDMO (C, F) for either 3 h (A–C) or 6–7 h (D–F), then labeled with Mitotracker. Bar = 50 µm. G) To quantitate the pattern of mitochondria distribution (white regions) in 2-cell embryos the average pixel intensity of the region within each of the four circles was determined. The ratio of the average pixel intensity of the intermediate region to the perinuclear region from the same side of the blastomere was determined. A ratio closer to one indicates a more homogeneous distribution of mitochondria, whereas a ratio closer to zero indicates a heterogeneous pattern, with a higher accumulation of mitochondria around the nucleus than in the intermediate region [31]. The graph (H) shows these ratios for embryos cultured for either 3 h or 6–7 h in HECM-10, HTMA, or HDMO. Numbers in parentheses are numbers of embryos; bars are standard error. *Significant difference from control at P < 0.05.