Developmental and Structural Section
Kitin, Peter , Takata, Katsuhiko .
Novel microcasting techniques for characterization of the three-dimensional structure of plant tissues.
PREVIOUS research shows that microcasting followed by scanning electron microscopy is very useful for studying the three-dimensional (3-D) structure of xylem vessels, vessel elements, and tracheids. In order to evaluate further the potential of microcasting, we examined different casting media (elastomer, epoxy resin, low-density polyethylene, and polystyrene) and different techniques for extraction of cell wall material. Each modification of the method was associated with certain advantages, and limitations. The elastomer and low-density polyethylene were appropriate for analysis of vessel networks, intercellular space networks, and 3-D morphology of vessel elements. These methods yielded clear images of features that have been poorly investigated, such as vessel ends, branched vessels, and twisted adjacent vessels. The epoxy and the styrene monomer penetrated pit membranes and primary cell walls; consequently the original pit contacts between imperforated xylem cells sustained the chemical treatment and remained intact in the casts. The latter two casting media were also applied for analysis of the intra- and intercellular spaces in phloem and differentiating cambial tissue. Polystyrene microcasts revealed details of cell wall structure with the highest fidelity, for example the ultrastructure of pits. However, with any microcasting method used to date, it was difficult to preserve the original spatial arrangement of cells in large samples. Therefore, for analysis of the course of xylem vessels, we combined the microcasting method with reconstructions from series of thick histological sections and epifluorescence or confocal microscopy. In several dicotyledon tree species investigated, vessel and tracheid networks extended across xylem growth-ring boundaries. In addition to water-conducting cells networks, other anatomical features that might affect gas or fluid movement in plant stems, such as intercellular spaces networks in xylem and phloem, and distribution and quantity of pits in the walls of tracheary elements, are illustrated and discussed.
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1 - Akita Prefectural University, Institute of Wood Technology, Kaieisaka 11-1, Noshiro-shi, Akita-ken, 016-0876, Japan
xylem structure and function.
Presentation Type: Oral Paper:Papers for Sections
Location: 312/Bell Memorial Union
Date: Monday, July 31st, 2006
Time: 5:00 PM