Torus Structure and Development in the Woods of Ulmus Alata Michx., Celtis Laevigata Willd., and Celtis Occidentalis L.

IAWA Journal ◽  
1990 ◽  
Vol 11 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Roland R. Dute ◽  
Ann E. Rushing
Keyword(s):  
Secondary Wall ◽  
Small Diameter ◽  
Three Dimensions ◽  
Central Layer ◽  
Tracheary Elements ◽  
Pit Membrane ◽  
Celtis Occidentalis ◽  
Celtis Laevigata ◽  
Ulmus Alata ◽  
Grooved Wheel

Pit membranes between tracheary elements of Ulmus alata, Celtis laevigata, and Celtis occidentalis often contained tori. The degree of development of tori varied and was greatest in those membranes connecting elements of small diameter. Complete tori consisted of two wall thickenings adjoined by a central layer. In three dimensions the shape of the torus often approximated a grooved wheel. Initiation of thickening in the pit membrane occurred first on the side of the older cell and was well underway prior to the beginning of secondary wall synthesis. Torus formation resulted from the thickening of the primary walls of the pit membrane. Development of the torus was associated with membranous vesicles and cisternae but not with microtubule complexes as was reported in Osmanthus. The pit membranes in this study are capable of aspiration, and the tori may prevent rupture of the pit membrane during this process.

Differences in the brain stem terminations of large- and small-diameter vestibular primary afferents

1995 ◽  
Vol 74 (3) ◽  
pp. 1362-1366 ◽  
Author(s):  
J. A. Huwe ◽  
E. H. Peterson
Keyword(s):  
Brain Stem ◽  
Large Diameter ◽  
Small Diameter ◽  
Movement Control ◽  
Three Dimensions ◽  
Significant Shift ◽  
Axon Diameter ◽  
Vestibular Complex ◽  
The Brain ◽  
Adjacent Brain

1. We visualized the central axons of 32 vestibular afferents from the posterior canal by extracellular application of horseradish peroxidase, reconstructed them in three dimensions, and quantified their morphology. Here we compare the descending limbs of central axons that differ in parent axon diameter. 2. The brain stem distribution of descending limb terminals (collaterals and associated varicosities) varies systematically with parent axon diameter. Large-diameter afferents concentrate their terminals in rostral regions of the medial/descending nuclei. As axon diameter decreases, there is a significant shift of terminal concentration toward the caudal vestibular complex and adjacent brain stem. 3. Rostral and caudal regions of the medial/descending nuclei have different labyrinthine, cerebellar, intrinsic, commissural, and spinal connections; they are believed to play different roles in head movement control. Our data help clarify the functions of large- and small-diameter afferents by showing that they contribute differentially to rostral and caudal vestibular complex.

The fine structure of the pits of Eucalyptus regnans (F. Muell.) and their relation to the movement of liquids into the wood

1960 ◽  
Vol 8 (1) ◽  
pp. 51 ◽  
Author(s):  
J Cronshaw
Keyword(s):  
Secondary Wall ◽  
Structural Features ◽  
Cellulose Microfibrils ◽  
Primary Wall ◽  
Detailed Structure ◽  
Eucalyptus Regnans ◽  
Pit Membrane ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

Observstion in the electron microscope of carbon replicas of the pits of vessels, ray parenchyma cells, fibres, and tracheids of Eucalyptus regnans has shown the detailed structure of the pit borders and the pit closing membranes. In all cases in the mature wood the primary wall is left apparently without modification as the pit membrane. Unlike the borders of the pits of fibre tracheids and tracheids, the pit borders of the vessels are not separate; the cellulose microfibrils of a border may be common to several pits. The pit borders of fibre traoheids and tracheids are developed as separate entities and have a structure similar to the pit borders of softwood tracheids. The structure of the secondary wall layers associated with the pits is described and related to the structure of the pits. The fine structural features of the pits, especially of the pit closing membranes, are discussed in relation to the movement of liquids into wood.

Structure and Ultrastructure of the Tracheary Elements of Asplenium (Pteridophyta) from the “Yungas”, Argentina

IAWA Journal ◽  
2010 ◽  
Vol 31 (2) ◽  
pp. 227-240 ◽  
Author(s):  
María Luján Luna ◽  
Gabriela Elena Giudice ◽  
María Alejandra Ganem ◽  
Elías Ramón de la Sota
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Maturation Stage ◽  
Tracheary Elements ◽  
Transmission Electron ◽  
Pit Membrane ◽  
Membrane Hydrolysis ◽  
Structure And Ultrastructure ◽  
Scanning Electron

The structure of root and rhizome tracheary cells of Asplenium spp. (Filicales, Pteridophyta) growing in NW Argentina was studied using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In all cases, tracheary cells consisted of tracheids with various facets, mainly with scalariform pitting. With SEM, intertracheary pit membranes appeared smooth and non porose in most cases. In some instances, porose or web-like to thread-like pit membranes were noticed in rhizome tracheids. Under TEM secondary walls displayed a smooth and uniform appearance. Pit membranes showed a variation in thickness in presumed association with their maturation stage. More mature tracheary cells showed pit membranes with a mesh-like aspect and visible openings or pores. These characteristics are attributed to pit membrane hydrolysis, which facilitates water transport among tracheary cells.

Fine structure of Tyloses in three species of the Myrtaceae

1967 ◽  
Vol 15 (1) ◽  
pp. 25 ◽  
Author(s):  
RC Foster
Keyword(s):  
Fine Structure ◽  
Granular Material ◽  
Double Layer ◽  
Layered Structure ◽  
Outer Layer ◽  
Secondary Wall ◽  
Pit Membrane ◽  
Ray Cell

The tylosis wall in Eucalyptus obliqua L'Herit. is shown to be composed of two microfibrillar layers. The outer layer (T1), with randomly orientated microfibrils, is covered with amorphous granular material. The inner layer (T2) is multilamellate. In sclerosed tyloses of E. miniata A. Cunn., each lamella of T2 is composed of many layers of microfibrils. Simple pits, delineated by circumferentially orientated microfibrils, are found in both sclerosed and non-sclerosed tyloses. The tylosis in E. obliqua is shown to arise from a two-layered structure formed within the secondary wall of the ray cell. This layer extends into the pit chamber, covering the pit membrane on the ray side. Following the breakdown of the vestures and the pit membrane, this double layer bulges out into the vessel to form the tylosis.

Sur la différenciation des trachéides dans les haustoriums d'Osyris alba parasitant Hedera helix

1987 ◽  
Vol 65 (8) ◽  
pp. 1746-1755 ◽  
Author(s):  
H. Benharrat ◽  
S. Renaudin ◽  
L. Rey ◽  
P. Thalouarn
Keyword(s):  
Golgi Apparatus ◽  
Secondary Wall ◽  
Multivesicular Bodies ◽  
Tracheary Elements ◽  
Hedera Helix ◽  
Second Stage ◽  
Host Root ◽  
Cytoplasmic Content ◽  
Cambial Cells ◽  
Surrounding Membrane

The central part of the haustorium of Osyris alba L. contains a cambium which is continuous from the mother root to the vicinity of the "absorbing cells." It centripetally differentiates tracheary elements which make up a vascular core, the xylem bridge, connecting the vessels of the parasite root to those of the host root. In the differentiating cambial cells, a first stage of activity of the Golgi apparatus, which is related to the development of the secondary wall thickenings, is evident. This stage is marked by the presence of numerous vesicles containing an electron dense material and of multivesicular bodies lying near the plasmalemma. The cells also contain numerous spherical granules which, while being mainly proteinaceous, also contain some potassium, calcium, and sulfur. The composition of these granules, the fact that their surrounding membrane is studded with numerous ribosomes and the fact that they often form short chains in a common membranous profile lead us to conclude that they are elaborated in the endoplasmic reticulum. Later in the course of differentiation of those cells, a second stage of activity of the Golgi apparatus can be observed, with the numerous vesicles showing a light content this time. This phase precedes a lysis process during which the cells lose all their cytoplasmic content. Only the granules remain in the differentiated tracheids. [Journal translation]

TORUS LIGNIFICATION IN HARDWOODS

IAWA Journal ◽  
2004 ◽  
Vol 25 (4) ◽  
pp. 435-447 ◽  
Author(s):  
Christina M. Coleman ◽  
Brian L. Prather ◽  
Matthew J. Valente ◽  
Roland R. Dute ◽  
Michael E. Miller
Keyword(s):  
Cell Maturation ◽  
Developmental Studies ◽  
Celtis Occidentalis ◽  
Daphne Odora ◽  
Ulmus Alata ◽  
Spurious Results

Tori in wood of Osmanthus americanus, Daphne odora, Celtis occidentalis and Ulmus alata were tested for lignins using KMnO4 staining in conjunction with TEM, and acriflavine staining in concert with CLSM. It was hypothesized that impregnation with lignin could explain torus survival during cytoplasmic apoptosis. KMnO4 staining indicated torus lignification in all four woods, whereas only Osmanthus and Daphne tested positive for lignin with acriflavine. Tori in Celtis and Ulmus showed some evidence of partial breakdown during cell maturation, which might expose non-lignin sites for KMnO4 binding and thus produce spurious results. The acriflavine data correlate with developmental studies in which torus ontogeny occurs by one method in Osmanthus and Daphne and by another method in Celtis and Ulmus.

Intervascular Pit Membrane Structure in Daphne and Wikstroemia - Systematic Implications

IAWA Journal ◽  
1996 ◽  
Vol 17 (2) ◽  
pp. 161-181 ◽  
Author(s):  
Roland R. Dute ◽  
John D. Freeman ◽  
Frank Henning ◽  
Logan D. Barnard
Keyword(s):  
Membrane Structure ◽  
Conducting System ◽  
Tracheary Elements ◽  
Pit Membrane ◽  
Vessel Elements ◽  
Close Relationship ◽  
Helical Thickenings ◽  
Isolated Species

Intervascular pit membranes were investigated in species of Daphne, Wikstroemia, and other allied genera of the Thymelaeaceae. Results confirmed a previous study showing that, except for section Mezereum, all sections of Daphne had pit membranes with tori. Taxonomically isolated species D. aurantiaca and D. genkwa had tori, but lacked a G-layer. Tori similar in structure to those of D. aurantiaca and D. genkwa were observed in three species from the subgenus Diplomorpha of Wikstroemia. Tori of a slightly different morphology were noted in W. kudoi (subg. Daphnimorpha). Tori appeared absent from species of the subgenus Wikstroemia (= Euwikstroemia of Domke), and from the genera Drapetes, Edgeworthia, and Eriosolena. These results suggest a close relationship between Daphne and Wikstroemia. The degree of torus development and the distinctiveness of helical thickenings suggest that smaller tracheary elements serve as a backup water-conducting system to larger vessel elements.

Torus Presence and Distribution in Leaves of Osmanthus Armatus

IAWA Journal ◽  
2012 ◽  
Vol 33 (3) ◽  
pp. 257-268
Author(s):  
Roland R. Dute ◽  
Paul J. Zwack ◽  
Ebony Craig ◽  
Steven M. Baccus
Keyword(s):  
Growth Habit ◽  
Small Diameter ◽  
Tracheary Elements ◽  
Cell Type ◽  
Leaf Veins

Osmanthus armatus Diels is a member of the Oleaceae whose woody branches were previously found to possess torus-bearing pit membranes. Observations of the perennial leaves indicate that torus-bearing, pitted tracheary elements extend throughout the vasculature of the organ including the veins delimiting the areoles and the vein termini. Torusbearing tracheary elements differentiate into the vein termini but do not develop at the very ends. Rather, the distal ends of vein termini consist of tracheids without tori and of phloem containing intermediary cells. The latter cell type is a component of the phloem in the small diameter leaf veins. Tori are considered to be xeromorphic features which, along with a thick cuticle and sclereids, are advantageous for the perennial growth habit of the leaves.

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