Developmental and Structural Section
Chen, Chyi-chuann , Chen, Yung-reui .
Study on the laminar hydathodes of Ficus formosana (Moraceae). II. Morphogenesis of epithem.
The development of laminar hydathodes in Ficus formosana Maxim. was examined with light and electron microscopies. Four main stages of hydathode developments are as follows: 1, initial stage; 2, cell division stage; 3, cell elongation and cell differentiation stage; and 4, maturation stage. In the early stage of leaf development, the initial cells occur in the region nearby a giant trichome. In cell division stage, epidermal initial cells are anticlinally divided to form epidermal cells and water pores and subepidermal initial cells through anticlinal and periclinal divisions produce a group of cells, which further differentiate into epithem, tracheid and a sheath layer of hydathodes. During cell elongation and differentiation stages, epithem cells grow into the lobe-shaped cells that their performs are caused by some factors, including on set of the special microtubule arrangement abounding pericytoplasm, secreted cell wall digesting enzymes for action and tension of cell growth. The lobe-shaped epithem cells increase the contact region between the cells and their environments. Tracheids are also starting differentiation and the differentiation rates of water pores are reaching maximal on epidermis. In the maturation stage, tracheids within epithem are gradually toward maturation with conductive function that is associated with maturation of epithem cells and water pores through the way between vein-ends and water pore to make sure guttation processing. It is worth mentioned that the way of epithem differentiation and maturation is starting from the regions under water pores to vein-end region. Guttation is processed until the epithem nearby vein-ends are maturation.
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1 - National Taiwan University, Institute of Molecular And Cellular Biology, Taipei, 106, Taiwan
Epithem, Hydathodes, Intercellular space.
Presentation Type: Oral Paper
Date: Monday, August 15th, 2005
Time: 3:45 PM