ISSN:
1615-6102
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary The ultrastructure of Strasburger cells (= albuminous cells) in the secondary phloem ofPinus nigra var.austriaca (Hoess) Badoux is described in different stages of differentiation and compared with that of ordinary ray parenchyma cells. Most characteristic for Strasburger cells contiguous with mature sieve cells in summer are the absence of starch, the presence of peculiar cytoplasmic bridges with the sieve cells, and a relatively dense protoplast; during differentiation the central vacuole fragments into many small vacuoles. In addition, these cells differ substantially by the abundance of polysomes which is paralleled by the highly decondensed state of the euchromatin and by the increased outer surface of their lobed nuclei. Mitochondria are fairly abundant. The small vacuoles always show dark lined tonoplasts. Cytoplasmic tubuli which nature is still unknown are described. Increased nuclear surface, highly decondensed euchromatin, and abundance of polysomes are taken to indicate an increased rate of transcription/translation events. This, together with the abundance of mitochondria suggests an increased physiological activity. Because these structural peculiarities could not be detected so far in Strasburger cells contiguous with immature sieve cells, nor in ordinary ray parenchyma cells, they are considered to be related to the peculiar function of active Strasburger cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01280358
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