• 作者： 鄭炳今; 林美瑛
• 作者服務機構： 加拿大 安大略省 西安大略大學 植物學系
• 中文摘要： 本研究在於探討猿猴草（Caltha palustris L.）小蕊的基本構造，同時對花葯角質層及營養細胞表面的球狀體做深入的超微結構觀察。並推論球狀體之形成機構。我們發現猿猴草的球狀體為一大小在 1μm左右、表面具有短刺狀凸起之多角形結構，在切片中顯示，此球狀體中具有一個（或多個）核心結構，而在核心中具有一團高電子密度物質，其中並具有一低電子密度（厚約7nm）的板狀構造，其功用不詳。立體攝影照片組顯示，球狀體的基質中有大量管狀結構，而此管狀結構由核心向外發散。球狀體核心中的高電子密度物質可被三氯甲烷溶掉，顯示此構造可能為脂質。由各項觀察結果，我們推論球狀體基質內的管狀構造是外壁質沉積之構架，所以，管狀構造之粗略形狀決定球狀體的基本外形。一般相信角質層是用以防止水份蒸散及防止病原侵入植物體之一層保護層，但其生理及物理特性吾人並不瞭解。本研究在探討花葯表面的角質層與花絲表面的角質層之結構，並詳細地觀察其切面細微結構及內、外表面之表面細微構造。我們發現，花葯與花絲的角質層中都具有高電子密度的網狀構造，此結構可能是細胞壁物質之延伸。花絲的角質具有寬 300 nm 之小脊狀凸起，而花葯表面則無。由氯化鋅－鹽酸所分離的花葯角質，其外表面具有不定形小凸起，因此，外表面相當粗糙；而內表面具有基部直徑 250 nm 錐狀凸起，花絲角質外表面除了小脊狀凸起之外，亦具有不定形小突起，而內表面可見到凹陷之部位，是為脊狀凸起之內面。 花葯之基本構造顯示花葯的開裂佈粉機能可能由於花葯表皮細胞因失水塌扁變形、葯隔與花粉囊間帶之表皮細胞下之氣室充氣或由於葯隔細胞膨大所致，但目前仍無法完全瞭解開裂之原
• 英文摘要： Ubisch was the first to describe a darkstaining body on the locular surface of tapetalcells in many flowering plants. This structureis known as the Ubisch body or orbicule. For general ultrastructural studies, anthersof both young-pollen and near-mature pollenstages were fixed in Cheng's fixative, post-fixedin and embedded in Spurr's medium. Thinsections were cut with glass or diamond knives,and stained with uranyl acetate-lead citrate or-lead citrate. Lead aspartate was usedfor en bloc staining. Semi-thin and ultrathinsections were obtained for both TEM and LMobservations. Stereo micrographs were preparedto reveal the 3-dimensional structure of theorbicules. The orbicules are appoximately 1 μm indiameter with spinule-like surface projectionslocated on the locular surface of the tapetalcell. A core with electron-dense material, asso-ciated with a network of tubular-like structures,was observed in the orbicules. The electron-dense material has a 7 nm thick“white lamellar”inclusion, the function of which is not clear.The electron-dense material of the core can bedissolved with chloroform, suggesting a“lipid-like”composition. The development of orbiculesbegins with the secretion of pro-orbicules fromthe tapetal cell; then, the orbicule matrix isdeposited on its surface. We propose that thetubular-like structure within the orbicules pro-vides a structural framework on which thematrix is deposited; hence, the external archi-tecture of the orbicules is determined by theshape of the tubular-like structure. The fine structure of the cuticle layer wasstudied by TEM using thin sections and surfacereplicas of isolated cuticles. A reticular network,which is believed to be cell wall material pene-trating the cuticle layer, can be observed inthe cuticle by TEM. The cuticle is a smoothlayer lacking noticable surface features whenviewed under low magnification SEM. However,high resolution TEM of cuticle surface replicasreveals numerous bumps on the outer surface.The inner surface of the cuticle facing the cellwall has many cone-shaped projections with abase diameter of 250nm; the structure of theseis not clear when viewed from thin sections.The surface of the filament cuticle is similar tothe anther surface in that it has many ridgedprojections. These ridges have a height andwidth of 300nm, and are parallel to the longaxis of the filament. The inner surface of thefilament cuticle, however, has many long troughscorresponding to the inner side of the cuticlarridges. The anther consists of four microsporangia.The tissue between the microsporangia is knownas the intermicrosporangial stripe (IMS). Thetwo lateral intermicrosporangial stripes are term-ed ; the abaxial one, ; and theadaxial one, It has been observed thatthe epidermis forms a separate layer whichis detached from the underlying connective tissue,thus forming an air sac. We suggest that eitheran increase in air volume in the sac creating aforce on the anther wall, or a volume increaseof the connective parenchyma cells functionsin anther dehiscence. The mechanism of antherdehiscence, and the morphological features ofanther and filament will be discussed in thisarticle.
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