In mitochondria-rich cells, cytoplasm degradation was observed, with disappearance or disorganization of endoplasmic reticulum network and mitochondrial degradation evidenced by mitochondrial crest
degeneration and dilation of intermembrane space (Figs.
A4: Level 3 (score 3) mitochondrial crest
is divided with transparent or thick substrate (white arrow).
Mitochondria were swollen and there was either reduction of mitochondrial crest
and matrix density or vacuolation.
The mitochondria observed in MeHg-treated embryos maintained the tubular morphology but exhibited loss of mitochondrial crests
and swelling in the mitochondrial matrix (Figures 2(b) and 2(e)-2(h)).
The following changes were also found during the electron microscope evaluation: clearly visible enlargement of the area of heterochromatin in the periphery of nuclei, atrophy and shortening of mitochondrial crests
, mitochondrial inclusions, and disruption of mitochondrial structure.