. Cytology. Cytology. (g) Figure 2-1. Plant and Animal Cells Exhibiting Differences in Shape: (a) oligodendrocyte from 5-day culture of rat brain tissue (corpus cal- losum); (b) unfertilized animal egg cell of starfish; (c) bacterial cells {Azobacter species); (d) giant multipolar motor nerve cells from ox spinal cord; (e) unicellular animal organism {Ameba species); (f) grouping of alga cells (Spirogyra); (g) nucleated erythrocytes of bird; (h) guard cells associated with leaf stomata. (Fig. (a) from Lumsden, C. E. and Pomerat, C. M., 1951. "Normal Oligodendrocytes in Tissue Culture,&quo
. Cytology. Cytology. (g) Figure 2-1. Plant and Animal Cells Exhibiting Differences in Shape: (a) oligodendrocyte from 5-day culture of rat brain tissue (corpus cal- losum); (b) unfertilized animal egg cell of starfish; (c) bacterial cells {Azobacter species); (d) giant multipolar motor nerve cells from ox spinal cord; (e) unicellular animal organism {Ameba species); (f) grouping of alga cells (Spirogyra); (g) nucleated erythrocytes of bird; (h) guard cells associated with leaf stomata. (Fig. (a) from Lumsden, C. E. and Pomerat, C. M., 1951. "Normal Oligodendrocytes in Tissue Culture," Cell Res., 2, Fig. 5, p. 109. Courtesy of Dr. C. M. Pomerat, Pasadena Foundation for Medical Research. Figs, (b) through (h), courtesy of General Biological Supply House, Inc., Chicago, 111.) In addition to the nucleus, the cytoplasm of the cell usually contains a number of distinct bodies or structures that presumably carry out one or more rather specific functions (Figure 2-2). These structures, which are discussed in Chapters 3 and 4, are frequently classified according to whether they are living (organelles) or dead (inclusions). Our lack of knowledge concerning ontogeny and function of many of them makes such a classification of dubious utility. For purposes of discussion, the components of the cytoplasm may be broadly classified, on the basis of light and electron microscope studies, as follows: (1) mitochondria, (2) plastids, (3) lysosomes, (4) endoplasmic reticulum, (5) "micro- somes," (6) cytoplasmic matrix, (7) Golgi complex, (8) cell mem- brane, (9) vacuoles, and (10) cytoplasmic inclusions. Although attempts to apply the methods of chemical analysis to living matter are almost as old as organic chemistry, it is only in recent years that major advances have been made in this direction. Quite apart from the innate complexity of protoplasm is the technical difficulty of obtain- ing analytic samples in "pure" form. The relative amounts of
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