DECAY PATTERNS OF FIBERS AND PARENCHYMA CELLS IN THE SAPWOOD OF QUERCUS-SERRATA BY LENTINUS-EDODES

Decay patterns of fibers and parenchyma cells in the sapwood of Quercu s serrata Thunb. by Lentinus edodes (Berk.) Sing. were compared by lig ht and scanning electron microscopies. The thinning of the fiber walls advanced usually from the lumen toward the middle lamella, and the de cay pattern was characterized by the appearance of multilamellate cell ulose microfibril (CMF) bundles in the secondary wall as the result of the selective removal of the matrix substances. Degradation of the ge latinous layer was slower than that of secondary walls. In axial and r ay parenchyma cells, cell contents were decomposed readily in the earl y stages of decay. The CMF bundles of the innermost wall layer were ex posed and finally degraded, but the next layer, the amorphous layer, w as resistant to fungal degradation. Therefore, the wall thinning from the lumen side seldom was recognized even in 4.8-year-old bedlogs. The characteristic thinning from outside of the cells was observed in mul ti- and uni-seriate ray parenchyma cells; cell corners were removed fi rst, and the wall degradation progressed toward the lumens. The differ ence in decay patterns between fibers and parenchyma cells may be attr ibuted to the presence of an amorphous layer in the walls of parenchym a cells.