Not only ray parenchyma cells in wetwood are partially de graded but also margo strands in pit membranes are somewhat degraded by bacterial activities.

• 细菌的活动不但使湿心材部位的部分射线薄壁细胞发生降解，而且纹孔膜塞缘的微纤丝束也偶尔被降解而产生断裂。