Transmission electron microscopic (TEM) images of mitochondrial changes in neurons after OGD.

<p>This figure shows representative TEM images of control and OGD cells. In control cells the mitochondria are mainly small, tubular, with normal density (A, top picture), however, there are some mitochondria that are larger and have normal, or increased intra-mitochondrial density (A, bottom picture). Following 1 h OGD there were several larger and elongated mitochondria in the cortical neurons (B). Several cells also showed the nuclear and cytoplasmic signs of apoptosis (condensed/peripheralized nuclear chromatin and/or cytoplasm, cytoplasmic vacuolization) or necrosis (decreased cytoplasmic density, no detectable plasma membrane) even after 1 h OGD. Following 3 h OGD several mitochondria are large, swollen, show a loss in their internal cristae structure, and their matrix is less dense compared with control (arrowheads). There are, however, several larger, but morphologically intact mitochondria with normal or high density, and some cells have both kinds of mitochondria (Fig. C). Furthermore, most of the cells following 3 h of OGD showed apoptotic or necrotic signs in the TEM pictures. With increasing time after 3 h OGD there were increased numbers of large, swollen mitochondria with rupture/loss of internal cristae (D, arrowheads), whereas some cells still had morphologically intact mitochondria (D, stars). Bars represent 500 nm, stars = mitochondria with intact internal membrane structure, arrowheads = damaged mitochondria, ch = nuclear chromatin, m = mitochondrion, N = nucleus. OGD = oxygen-glucose deprivation.