Study On The Structure Of Bordered Pit Membrane And Micropores On Margo Of Cunninghamia Lancelata Tracheid

In order to better understand the structure of the bordered pit membrane and Micropores on margo of Cunninghamia lanceolata. The structure was studied through the observation using scanning electron microscope. The better scanning electron microscope pictures are obtained. At the same time, we still study the micropore on pit membrane of the fresh wood utilizing micro-graphics analysis. Compare the bordered pit membrane between fresh wood and air-dried wood , the following conclusions are drawn:1. The bordered pit membrane of the air-dried wood are covered with amorphous materials, the vague microfibrils can be seen on the margo. There are more amorphous materials on heartwood pit membrane than on sapwood. Torus combine with margo as one whole hard crust. The torus on the earlywood are sunken as one dish while no close torus is discovered on the latewood. The hollows can be found on torus of the heartwood.2. There is no special thickness on the torus of the bordered pit membrane on the fresh wood. The thickness change from torus to margo is not obvious. There are 3-4 layers microfibrils on the pit membrane. The microfibrils of the margo mainly distribute radiately, part of them exist tangently and slantingly. The pores on the pit membrane of the sapwood are in open state. The pit membrane between sapwood and heartwood are covered with amorphous materials, but a few of open pores are found . As for heartwood, the pit membrane are covered with amorphous materials too.3. The microfibrils can be seen clearly when the amorphous materials are removed on the bordered pit membrane of the air-dried wood. The partly dissolve of the tumour layer utilizing sodium hypochlorous proved that there is lignin in the tumour layer. After removal of the amorphous materials, the nondirective-arrayed microfibrils and mesh-like pit can be observed. These characteristic proved that the torus are formed from primary cell wall.4. The area of the pore on the bordered pit membrane of the sapwood have a variety from 10^-4 μm² to 10^-1 μm². The area of pore on the earlywood(0.081 μm²) is larger than that on the latewood(0.067 μm²). As for the quantity of the pore on the bordered pit membrane,the earlywood has 6.50*10'Mv / cm2, while the latewood has 5.01*107>h / cm2.5. The average Ferets diameter and Diameter equivalent to a circle and Average chord length and Breadth of the pore on the bordered pit membrane of the sapwood almost all distribute to 0.09-0.2 wn and the size of earlywood is larger than that of latewood.6. There is no much difference between the earlywood and latewood in the pore shape. The pores look like rhombus and polygon.