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Title: | 樟樹葉片之分泌細胞 Secretory cells in the leaf of Cinnamoumum camphora (L.) Nees & Eberm. |
Authors: | Yi-wen Kuo 郭綺雯 |
Publication Year : | 1991 |
Degree: | 碩士 |
Abstract: | 本研究探討樟樹?Cinnamomum camphora (L.)Nees & Eberm.?葉片之形態及解剖,並特別關注於分泌細胞之微細構造與發育。 樟葉有背腹面之分,氣孔及毛茸都分佈於背軸面表皮,葉片成熟時毛茸脫落,並且表皮均覆被蠟質;葉肉細胞分成兩部份:柵狀組織排列緊密,分佈在向軸面表皮下,海綿組織排列疏鬆,分佈在背軸面表皮下,多為薄壁細胞;葉緣處則由厚壁組織組成;未成熟葉片的某些葉肉細胞中含有單寧質,在葉片成熱後則消失。 此外,樟葉還具有兩類較一般薄壁細胞大的異型分泌細胞,即油質細胞及黏液細胞,其中油質細胞數量較黏液細胞多;一般而言,此兩類細胞在葉片中呈隨機分佈,但黏液細胞於葉緣附近偏多;分泌細胞很早就開始發育;在枝稍可觀察到各種不同發育階段的分泌細胞,甚至已成熟的油質細胞,成熟的黏液細胞則在展開的葉片中才可發現。成熟的分泌細胞皆具有外,中,內三層細胞壁,內,外層以纖維素為主,中層細胞壁則為木栓層,此三層細胞壁在分泌作用進行前就依序完成堆積。 在發育早期分泌作用並不明顯,胞器也沒有明顯差異;很難區分出兩類分泌細胞,早期發育的分泌細胞除特殊的細胞壁及較大體積外,以染色較深的細胞質,較大的細胞核與核仁,較少葉綠層及澱粉粒的顆粒體等特徵,與鄰近細胞區別。本研究依細胞壁堆積情形,將早期發育的分泌細胞分成四個發育階段; 當分泌作用開始進行後,即可由細胞分泌物及微細構造,區分出油質細胞與黏液細胞。兩類分泌細胞都是由細胞質司分泌作用,分泌物聚集在細胞膜與細胞壁之間,不同的是:油質細胞的內層細胞壁向細胞內部延伸出杯狀突起,並且分泌物只在此處的細胞壁與細胞膜間聚集,形成油質腔,擴大的油質腔漸取代中央液胞位置;迫使細胞質擠向細胞週邊;黏液細胞並不形成杯狀突起,黏液則全面均勻地分佈在整個細胞壁與細胞膜之間,並將細胞質擠向細胞中央。在細胞分泌作用開始進行後,則依細胞質變化情形,各分成幾個發育階段。 油質細胞中可能參與分泌作用的主要胞器為顆粒體,黏液細胞則為高爾基氏體,油質主要成份為?草類化合物,黏液則為多醣類;當分泌細胞完全成熟後,細胞質瓦解;整個細胞腔則充滿油質或黏液,由於木栓層的不通透性及細胞質連絡絲之封閉,分泌物並不會流出細胞腔外。 The morphology and anatomy of the leaf in Cinnamomum camphora (L.) Nees & Eberm. were studied, with special reference to development of the secretory cell, on both light and electron microscopies. The leaves of C. camphora are dorsiventral. The stoma and trichome are confined to the abaxial surface .The trichomes absciss in a well developed leaf, and the leaf surface is coated by wax. The mesophyllous cells can be divided into two parts: the palisade tissue located at the adaxial side, and the sponge tissue located at the abaxial side. These tissues mainly consist of parenchyma, but the leaf edge is occupied by sclereids. In juvenile leaf, some mesophyllous cells contains tannin, which disappears after leaf become well developed. Besides, the leaves exhibit two types of idioblastic secretory cells: oil cells and mucilage cells. The oil cells are more abundant than mucilage cells. Generally these cells randomly distribute throughout the leaf tissue. However, the mucilage cells are more abundant in leaf margin. Two types of secretory cells show various stages in differentiating process in a given area. The mature oil cells can be found in the shoot apex, but the mature mucilage cells are only seen in the expended leaves. The three-layered wall appears as a significant characteristic of mature secretory cells: an outer cellulose layer, a suberized middle layer and an inner cellulose layer. These walls have been completely deposited before the onset of secretion. At the early developmental stage, secretion is not conspicuous, so that two types of secretory cells look alike morphologically. In addition to the three-layered wall and their large size, the young secretory cells differ from neighbouring parenchyma cells in their deeply staining cytoplasm, large nucleus and nucleolus, distinct plastids which lack thylakoid and have low starch content. Based on different deposition of the cell wall, four developmental stages are distinguished. The secreting substance comes from cytoplasm, and accumulated in the space between plasmalemma and cell wall. When the secretion begins, two types of secretory cells can be distinguished, not only from their contents but also from their ultrastructures. In oil cells, the “cupule” protrued from inner wall, and the oil substance accumulated at this place only. As the oil increases it occupies the central vacule and enforces the cytoplasm to the periphery of cell. The mucilage cells do not bear the “cupule”. Their secreting substance is located between the plasmalemma and the cell wall, and enforces the cytoplasm to the center of cell. Several developmental stages are also distinguished on the changes of cytoplasm. It is likely that the main organelle associated with oil secretion is plastid. On the other hand, dictyosomes function in the secretion of mucilage. The major composition in oil cell and mucilage cell are terpene and polysaccharide respectively. When secretory cell mature, the cytoplasm becomes degenerated. Finally, the lumen of idioblast becomes a large cavity, fulls with oil or mucilage, and is enclosed tightly by the impermeable suberin layer. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/75850 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 植物科學研究所 |
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