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ULTRASTRUCTURE OF THE CORALLINACEAE (RHODOPHYTA) II. VEGETATIVE CELLS OF LITHOTHRIX ASPERGILLUM 1
Author(s) -
Borowitzka Michael A.,
Vesk Maret
Publication year - 1979
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.1979.tb02978.x
Subject(s) - ultrastructure , biology , vacuole , cytoplasm , organelle , meristem , cell wall , chloroplast , anatomy , microbiology and biotechnology , botany , biochemistry , shoot , gene
The ultrastructure of the calcareous red coralline alga Lithothrix aspergillum Gray and the development of the various tissue types has been studied. The sub‐apical meristematic tissue alternately produces genicular or intergenicular cells. The genicular cells rapidly elongate and their cell walls thicken and become denser as more fibrillar wall material is laid down within the cell wall. These cells contain little cytoplasm and few organelles. The inter genicular cells which elongate only slightly during development have a small vacuole and many free starch grains in the cytoplasm. The peripheral cells in each inter genicular layer remain meristematic and form a cortical cell layer over the genicular cells. These cortical cells and the apical meristematic cells are covered by small epidermal cells which have extensive cell wall ingrowths between the chloroplasts. The inter genicular cells are calcified. Although the CaCO 3 is laid down within the cell walls, there is always a thin layer of CaCO 3 ‐free organic cell wall material between the plasmalemma and the CaCO 3 impregnated wall. Only the distal tips of the genicular cells are calcified. In old genicular tissues of Lithothrix, secondary deposits of CaCO 3 of unknown crystallography are also found in the spaces between the cell walls. Thus there appear to be at least two mechanisms of calcification in this alga.