Differentiating xylem elements of Avena coleoptiles have been examined by light and electron microscopy. Fixation in 2 per cent phosphate-buffered osmium tetroxide and in 6 per cent glutaraldehyde, followed by 2 per cent osmium tetroxide, revealed details of the cell wall and cytoplasmic fine structure. The localized secondary wall thickening identified the xylem elements and indicated their state of differentiation. These differentiating xylem elements have dense cytoplasmic contents in which the dictyosomes and elements of rough endoplasmic reticulum are especially numerous. Vesicles are associated with the dictyosomes and are found throughout the cytoplasm. In many cases, these vesicles have electron-opaque contents. "Microtubules" are abundant in the peripheral cytoplasm and are always associated with the secondary wall thickenings. These microtubules are oriented in a direction parallel to the microfibrillar direction of the thickenings. Other tubules are frequently found between the cell wall and the plasma membrane. Our results support the view that the morphological association of the "microtubules" with developing cell wall thickenings may have a functional significance, especially with respect to the orientation of the microfibrils. Dictyosomes and endoplasmic reticulum may have a function in some way connected with the synthetic mechanism of cell wall deposition.
Article|
March 01 1965
THE FINE STRUCTURE OF DIFFERENTIATING XYLEM ELEMENTS
James Cronshaw,
James Cronshaw
From the Department of Biology, Yale University, New Haven, Connecticut
Search for other works by this author on:
G. Benjamin Bouck
G. Benjamin Bouck
From the Department of Biology, Yale University, New Haven, Connecticut
Search for other works by this author on:
James Cronshaw
From the Department of Biology, Yale University, New Haven, Connecticut
G. Benjamin Bouck
From the Department of Biology, Yale University, New Haven, Connecticut
Received:
March 20 1964
Online ISSN: 1540-8140
Print ISSN: 0021-9525
Copyright © 1965 by The Rockefeller Institute Press
1965
J Cell Biol (1965) 24 (3): 415–431.
Article history
Received:
March 20 1964
Citation
James Cronshaw, G. Benjamin Bouck; THE FINE STRUCTURE OF DIFFERENTIATING XYLEM ELEMENTS . J Cell Biol 1 March 1965; 24 (3): 415–431. doi: https://doi.org/10.1083/jcb.24.3.415
Download citation file: