Mitochondria electron microscopy

FIG. 4. Ultrastructure of vascular smooth muscle of the rabbit inferior vena cava revealed with electron microscopy. Serial cross-sections of VSMCs are shown in series 1 (panel A—D) and series 2 (panel E—G). Series 1 illustrates the close spatial apposition between the superficial SR sheet and the PM with the apices of the caveolae perforating through the superficial SR sheets to come into contact with the bulk cytoplasm. The membranes of the PM (dotted line) and the SR (solid line) in panel A-D are outlined to the right of the respective panels. The close apposition between the superficial SR sheet, the PM and the neck region of the caveolae creates a narrow and expansive restricted space. Series 2 illustrates the perpendicular sheets of SR, which appear to arise from the superficial SR sheets. Mitochondria also come into close contact with the perpendicular SR sheets. Panel H contains a stylized illustration of the close association between the superficial SR sheet, which is continuous with the perpendicular sheet, the perforating caveolae (C), the PM and a mitochondrion (M). Panel I shows calyculin-A mediated dissociation of the superficial SR sheets from the PM (see arrows). The black scale bar indicated represents 200 nm of distance. 

Fig. 4 Transmission electron microscopy of a longitudinal section of the posterior end of a Cryptosporidium parvum sporozoite showing immunogold localization of pyruvate NADP+ oxidoreductase (CpPNO). The mitochondrion-like organelle ( ) is posterior to the nucleus, and lies between the nucleus and the CB. It is labeled by mitochondrion-specific 15-nm gold anti- particles. Small -nm gold goat anti-CpPFO particles (arrows) show the localization of CpPNO. There are no 6-nm particles localized within the mitochondrion-like organelle (reprinted from Fig. 12 of Ctrnacta et al. 2006 with permission of the publishers)...

Mitochondria are present in all eukaryotic cells that use oxygen in respiration, but the number per cell and the form and size vary.1-4 Certain tiny trypanosomes have just one mitochondrion but some oocytes have as many as 3 x 105. Mammalian cells typically contain several hundred mitochondria and liver cells5 more than 1000. Mammalian sperm cells may contain 50-75 mitochondria,6 but in some organisms only one very large helical mitochondrion, formed by the fusion of many individual mitochondria, wraps around the base of the tail. Typical mitochondria appear to be about the size of cells of E. coli. However, study of ultrathin serial sections of a single yeast cell by electron microscopy has shown that, under some growth conditions, all of the mitochondria are interconnected.7... 

Electron microscopy of radish radicle. Details of roots from seeds treated with 1/14-diluted reverse osmosis fraction, (a) Cortical cells showing protein-body-derived vacuoles (V) with remnants of electron-opaque protein material. Extremely swollen mitochondria (M) look like vacuoles with fine granular contents, (b) Detail of epidermal cell, showing swollen mitochondria (M), lipid droplets (L) and two dictyosomes (D). (c) The area enclosed in the rectangle in (b) is enlarged to show the two-membrane envelope and residual cristae (arrows) in a swollen mitochondrion. 

Kinetoplast a structure at the base of the single flagellum of a trypanosome. The K. has a high affinity for basic dyes, and was first observed early in the 20th century by light microscopy. Electron microscopy shows that the K. is a disc-like structure in the matrix of the cell s single mitochondrion. The K. has attracted biochemical interest because it contains an unusual form of highly catenated DNA, known as kinetoplast DNA (kDNA). See Catenane. 

The picture obtained by electron microscopy is static, whereas the real mitochondrion is a dynamic body that bends or straightens its structure and can be displaced throughout the cytoplasmic field. Motion pictures of mitochondria have even demonstrated mitochondrial fragmentation in both long and short axes and fusion of small mitochondria to form larger mitochondria. Mitochondria can travel from the cellular to the nuclear membrane where they appear to come in close contact with the nucleolus. The cause and the significance of these movements remain unknown. 

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