Ultrastructural changes in secondary wall formation of Phyllostachys pubescens Mazel fiber were investigated with transmission electron microscopy. Fiber developed initially with the elongation of cells containing...Ultrastructural changes in secondary wall formation of Phyllostachys pubescens Mazel fiber were investigated with transmission electron microscopy. Fiber developed initially with the elongation of cells containing ribosomes, mitochondria and Golgi bodies in the dense cytoplasm. During the wall thickening, the number of rough endoplasmic reticulum and Golgi bodies increased apparently. There were two kinds of Golgi vesicles, together with the ones from endoplasmic reticulum formed transport vesicles. Many microtubules were arranged parallel to the long axis of the cell adjacent to the plasmalemma. Along with the further development of fiber, polylamellate structure of the secondary wall appeared, with concurrent agglutination of chromatin in the nucleus, swelling and disintegration of organelles, while cortical microtubules were still arranged neatly against the inner side of plasmalemma. Lomasomes could be observed between the wall and plasmalemma. The results indicated that the organelles, such as Golgi bodies together with small vesicles, rough endoplasmic reticulum and lomasomes, played the key role in the thickening and lignification of the secondary wall of bamboo fiber, though cortical microtubules were correlative with the process as well.展开更多
The ultrastrncture of the skin of air-adapted mammals （bats） is not known. The study at the electron microscope of the skin of the back and the flying membrane of Pipistrellus kuhlii showed that the thickness of the...The ultrastrncture of the skin of air-adapted mammals （bats） is not known. The study at the electron microscope of the skin of the back and the flying membrane of Pipistrellus kuhlii showed that the thickness of the epidermis is very low （10- 12μm）, and that 1 - 2 flat spinosus cells are present beneath the stratum corneum which is formed by very thin corneoeytes that resemble those of avian apteric epidermis. The stratum granulosum is discontinuous and few small （less than 0.3μm large） keratohyalin granules are present. The epidermis is reduced to one flat basal layer in contact with the stratum corneum in many areas of the flying membrane. Transitional corneoeytes are almost absent suggesting that the process of eornification is very rapid. In the basement membrane numerous hemidesmosomes are present and form attachment points for the dense dermis underneath. Numerous collagen fibrils directly contact with the hemidesmosomes and the dense lamella of the basement membrane. Sparse elastic fibrils allow the stretching of the epidermis during flight and the rapid folding of the epidermis after flying without damaging the epidermis. Like in avian epidermis, the production of lipids is high in bat keratinocytes, and multilamellar bodies discharge lipids extra- and intra-cellularly. This may compensate the lack of a thick fat layer in the dermis of the flying membrane as lipids may help in thermical insulation against the cooling air currents flowing on the bat skin during flight. Fur hairs are very thin （4 - 7 μm）, and they have an elaborated cuticle made of pointed expansions similar in texture with that of the cortex. Cuticle ceils form hook-like grasping points that allow to keep hairs stuck together. In this way the pelage remains compact in order to maintain body temperature.展开更多
文摘Ultrastructural changes in secondary wall formation of Phyllostachys pubescens Mazel fiber were investigated with transmission electron microscopy. Fiber developed initially with the elongation of cells containing ribosomes, mitochondria and Golgi bodies in the dense cytoplasm. During the wall thickening, the number of rough endoplasmic reticulum and Golgi bodies increased apparently. There were two kinds of Golgi vesicles, together with the ones from endoplasmic reticulum formed transport vesicles. Many microtubules were arranged parallel to the long axis of the cell adjacent to the plasmalemma. Along with the further development of fiber, polylamellate structure of the secondary wall appeared, with concurrent agglutination of chromatin in the nucleus, swelling and disintegration of organelles, while cortical microtubules were still arranged neatly against the inner side of plasmalemma. Lomasomes could be observed between the wall and plasmalemma. The results indicated that the organelles, such as Golgi bodies together with small vesicles, rough endoplasmic reticulum and lomasomes, played the key role in the thickening and lignification of the secondary wall of bamboo fiber, though cortical microtubules were correlative with the process as well.
文摘The ultrastrncture of the skin of air-adapted mammals （bats） is not known. The study at the electron microscope of the skin of the back and the flying membrane of Pipistrellus kuhlii showed that the thickness of the epidermis is very low （10- 12μm）, and that 1 - 2 flat spinosus cells are present beneath the stratum corneum which is formed by very thin corneoeytes that resemble those of avian apteric epidermis. The stratum granulosum is discontinuous and few small （less than 0.3μm large） keratohyalin granules are present. The epidermis is reduced to one flat basal layer in contact with the stratum corneum in many areas of the flying membrane. Transitional corneoeytes are almost absent suggesting that the process of eornification is very rapid. In the basement membrane numerous hemidesmosomes are present and form attachment points for the dense dermis underneath. Numerous collagen fibrils directly contact with the hemidesmosomes and the dense lamella of the basement membrane. Sparse elastic fibrils allow the stretching of the epidermis during flight and the rapid folding of the epidermis after flying without damaging the epidermis. Like in avian epidermis, the production of lipids is high in bat keratinocytes, and multilamellar bodies discharge lipids extra- and intra-cellularly. This may compensate the lack of a thick fat layer in the dermis of the flying membrane as lipids may help in thermical insulation against the cooling air currents flowing on the bat skin during flight. Fur hairs are very thin （4 - 7 μm）, and they have an elaborated cuticle made of pointed expansions similar in texture with that of the cortex. Cuticle ceils form hook-like grasping points that allow to keep hairs stuck together. In this way the pelage remains compact in order to maintain body temperature.
