Intramitochondrial inclusions in various cells of a snake (Elaphae quadrivirgata)

Giant mitochondria and intramitochondrial inclusions in benign thyroid lesions

Enlarged mitochondria and intramitochondrial dense structures have been reported to occur in a great variety of animal and human cells under normal, pathologic, and experimental conditions. Three cases of benign thyroid lesions are described in which large cytoplasmic inclusions were seen on light microscopy. These inclusions were stained with toluidine blue but not with Sudan black B, as was seen in consecutive sections. Ultrastructural observation showed that they corresponded to giant mitochondria. Bundles of dense filaments and round, electron-dense bodies were observed in the matrix of the enlarged mitochondria. Incubation of ultrathin sections with proteolytic enzymes (pepsin, trypsin, and type XVI-protease) led to a striking decrease in the electron density of both types of intramitochondrial matrical structures. These observations demonstrate that a major proteic component exists in intramitochondrial filamentous bundles and in dense bodies.

Prismatic cristae and paracrystalline inclusions in mitochondria of myocardial cells of the oyster Crassostrea virginica Gmelin

Several types of unusual mitochondrial configurations were found in myocardial cells of the oyster Crassostrea virginica Gmelin. These mitochondria include, in order of frequency, prismatic cristae, filamentous paracrystals in honeycomb and herringbone configurations, and paracrystals composed of rows of electron dense particles. The long, parallel, evenly spaced prismatic cristae are square or rhomboidal in cross section. In the space between the prismatic cristae are rodlike structures (4--6 nm in diameter) that are regularly spaced about 12 nm apart and appear to pass between adjacent cristae. Filamentous paracrystals observed in slender, elongated mitochondria. The filament spacing and form of these paracrystals suggest that they are composed of the intercristal rods. Alternatively, filamentous paracrystals might be tangential sections of prismatic cristae and intercristal rods. Particulate paracrystals which consist of dense lines or rows of particles are the least frequent type of unusual configuration. The particles are triangular, possibly pyramidal, in shape; their bases are 10-12 nm thick and repeat in rows every 17-18 nm. There is a close association between particulate paracrystals and prismatic cristae plus intercristal rods. Although similar mitochondrial configurations have been associated with disease or altered metabolism in a number of species, we have found so such association in the oyster as yet.

The occurrence of paracrystalline mitochondrial inclusions in normal human skeletal muscle

Two different types of paracrystalline mitochondrial inclusions identical with or very similar to those already described in the literature for a variety of muscle diseases were found in human skeletal muscle biopsies obtained under general anesthesia before ischemia and after various periods of anoxia up to 150 min. As these crystalloids could be observed in seven of 14 healthy subjects and occurred in five of these seven cases either before or only 10 min after onset of ischemia, it is suggested that such mitochondrial inclusions develop not only under the influence of variant noxious stimuli, but may also represent a normal constituent of human skeletal muscle mitochondria.

Intramitochondrial yolk-crystals of frog oocytes. I. Formation of yolk-crystal inclusions by mitochondria during bullfrog oogenesis

Electron microscope examination of thin sections of bullfrog (Rana catesbeiana) ovarian oocytes has shown the presence of mitochondria containing yolk-crystal inclusions in oocytes of all sizes, from 160 to 1500 micro mean diameter. The hexagonally shaped yolk-crystals have major periodicities of 73.8 +/- 10.7 A (n = 100). Several forms of modified mitochondria, observed in the smaller oocytes, may be arranged into a series of structurally intermediate forms between standard oocyte mitochondria and the typical mitochondria with yolk-crystal inclusions. The observation of such intermediate forms is consistent with proposals that the yolk-crystal inclusions arise within a limited portion of the oocyte chondriome by a complex process of mitochondrial differentiation.