Structural Variations and Secondary Changes in Pit Membranes in Fraxinus Mandshurica Var. Japonica

Abstract

Structural variations and secondary changes in intervascular, interfibre, interparenchyma, vessel-parenchyma, and fibre-parenchyma pit membranes, from the outermost sapwood to the inner heartwood of Fraxinus mandshurica var.japonica, were studied by uitraviolet light microscopy, and by scanning and transmission electron microscopy. In the sapwood, none of the pit membranes appeared lignified and pit membranes were seldorn incrusted. In the heartwood, material that strongly absorbed ultraviolet light was heavily deposited on intervascular, interparenchyma, vessel-parenchyma, and fibre-parenchyma pit membranes. Secondary changes in the interfibre pit pairs were not so pronounced. Interfibre pit membranes were often absent in both the sapwood and the heartwood.