FREEZE-ETCHING AND REPLICATION STUDY OF WALL DEPOSITION IN ELONGATING PLANT-CELLS

  • 1 January 1978
    • journal article
    • research article
    • Vol. 22  (85) , 7-15
Abstract
The architecture of the expanding wall of mung bean hypocotyl (Phaseolus aureus) and collenchyma of celery (Apium graveolens) was examined using freeze-etching without any cryoprotectant, and surface-replication of frozen-ground and air-dried specimens. The polylamellated organization of the wall was seen. Freeze-etching clearly visualized, within 1 single fracture plane, the intermediate strata in which the microfibril orientation gradually changes between the main transverse and longitudinal directions. They corresponded to the bow-shaped arcs seen with surface replication and conventional microtomy. The organization of newly-formed microfibrils (periplasmic microfibrils) was seen by their imprints on the plasmalemma. When they were being deposited the microfibrils were loose and sinuous though tightly packed, rigid and parallel on the further layers. Apparently the fibrillogenesis and the spatial orientation of the microfibrils are 2 subsequent steps. The role of the periplasm in controlling the 3-dimensional arrangement of the wall is emphasized.