ABSTRACT
The balsam fir (Abies balsamea), a transcontinental gymnosperm, is economically important because of its value as a source for lumber and wood pulp. Besides its economic value, balsam fir, like many other conifers, contains the embryonic tissue that will produce the mature structures during the next growing season within relatively dormant vegetative buds. These buds have several advantages that make them very attractive for the preparation and study of plant ultrastructure. Thus, transmission electron spectroscopy (TEM) of buds is presented as an example of plant electron microscopy. Methods for the preparation of a wide variety of plant tissues can be found in the supplementary references to this chapter (Table 1.1). For a discussion of plant cell fractionation and the assay of organelle fractions for purity, the reader is referred to the review by Quail. 1
One advantage is the ease of handling because of the ideal size of the buds. They are large enough to treat as macroscopic structures, but small enough to allow good TEM fixation without a labor-intense effort. Terminal buds have a mean height of 2.60 mm. Because they have relatively well-described developmental cycles, gymnosperm buds can be collected and prepared at intervals that coincide with temporal-related cytological information. Since the preburst bud has a localized region (the apical dome) which contains an abundance of undifferentiated cells, many difficulties associated with the fixation and sectioning of differentiated plant tissues are avoided. Also, the
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TABLE1.1 SummaryofAncillaryElectronMicroscopicTechniques TechniqueRef.
