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Mammalian fast and slow twitch skeletal muscles are compared by freeze-fracture, thick and thin sectioning, and histochemical techniques using conventional and high voltage electron microscopy. Despite gross morphological differences in endplate structure visualized at relatively low magnifications in this sections, rat extensor digitorum longus (EDL) (fast(More)
Cell division in log-phase cultures of the unicellular, biflagellate alga, Chlamydomonas reinhardi, has been studied with the electron microscope. The two basal bodies of the cell replicate prior to cytokinesis; stages in basal body formation are presented. At the time of cell division, the original basal bodies detach from the flagella, and the four basal(More)
Yolk proteins are thought to enter certain eggs by a process akin to micropinocytosis but the detailed mechanism has not been previously depicted. In this study the formation of protein yolk was investigated in the mosquito Aedes aegypti L. Ovaries were fixed in phosphate-buffered osmium tetroxide, for electron microscopy, before and at intervals after a(More)
This paper reports an electron microscope examination of the cortices of some plant cells engaged in wall formation. Previous studies of similar material fixed in OSO(4) alone have disclosed discontinuities in the plasma membrane and other evidence of inadequate fixation. After glutaraldehyde, used as a fixative in this present study, the general(More)
Treatment of epithelial BSC-1 cells with low concentrations of the detergent Brij 58 results in partial or complete removal of the plasmalemma and partial extraction of internal membrane-bound organelles without causing massive release of "cytosolic" proteins from the cytoplasmic ground substance. Stereoscopic high-voltage electron microscopy of such(More)
In this work we look into the problem of why proteins, unlike small molecules, diffuse in the cytoplasm much more slowly than in aqueous solutions. In order to examine whether the cytoplasmic matrix could, by simple obstruction, retard protein diffusion to such an extent, we developed a method to measure semiquantitatively the fractional volume occupied by(More)
Several types of striated muscle have been examined by the technics of electron microscopy and the findings in myotome fibers of Amblystoma larvae, the sartorius, and cardiac muscle of the rat are reported on in some detail. Particular attention has been given to structural components of the interfibrillar sarcoplasm and most especially to a finely divided,(More)