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FINE STRUCTURE STUDIES OF PHLEUM ROOT MERISTEM CELLS. I. MITOCHONDRIA
Author(s) -
Avers Charlotte J.
Publication year - 1962
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1962.tb15039.x
Subject(s) - cytoplasm , biology , mitochondrion , staining , osmium tetroxide , biophysics , electron microscope , microbiology and biotechnology , physics , genetics , optics
A vers , C harlotte J. (Douglass Coll., Rutgers—The State U., New Brunswick, N.J.) Fine structure studies of Phleum root meristem cells. I. Mitochondria. Amer. Jour. Bot. 49(9): 996–1003. Illus. 1962.—Mitochondrial numbers were computed from thick sections embedded in paraffin and stained with iron hematoxylin, from methacrylate embedded, 0.5 μ‐thick sections stained with osmium, and from electron micrographs of ultrathin sections fixed in KMnO 4 . The mean mitochondrial counts per average cell (20 × 20 × 10μ) were: 121 ± 4 in paraffin sections, 600 ± 40 in methacrylate sections, and 991 ± 96 from electron micrographs. These numbers were higher than the Janus green B count of 91 ± 2 per cell found during an earlier study. In each case, arithmetical conversion factors were used to calculate total numbers of mitochondria per cell since section thicknesses were less than that of whole cell length or depth. Determinations of numbers of mitochondria probably varied depending on section thickness and specific staining procedures used, but the higher count from electron micrographs was assumed to be reasonable on a volumetric basis. The cytoplasmic volume of the average cell is about 2500 μ 3 and the volume of a single average mitochondrion is about 0.1μ 3. On this basis, the variety of structures and their relatively sparse distribution seems possible despite the apparently high numbers found. In addition to mitochondria, the numbers of various cellular components per unit cytoplasmic area were determined. These data showed that mitochondria were about 6 times more numerous than proplastids, about 4.5 times more numerous than Golgi bodies, and even more frequent when compared with vesicles, dense bodies, or microbodies. No correlation was found between cytoplasmic area and numbers of organelles per unit area. Photographic evidence was presented for the occurrence in plant cells of the hepatic cell, polymorphic “lysosome” described by Ashford and Porter. The controversial nature of the lysosome is discussed.