胖大海三种扫描电镜制样方法的观察比较

Observation and comparison of the Semen Sterculiae Lychnophera prepared by 3 kinds of scanning electron microscope methods

以直接烘干、常规生物电镜样品制备和烘干加锇酸熏染电镜样品制备三种方法分别处理梧桐科植物胖大海干燥成熟种子,进行扫描电镜观察和比较分析。结果显示:胖大海外层种皮薄而脆,表面具不规则细皱纹,表皮细胞呈多边形,腺鳞和气孔丰富,有少量星状非腺毛;中层种皮较厚,细胞大小不一,壁薄易破,呈管状簇网状排列,其间分布有革质带、革质筛孔、螺纹及环纹导管,吸水后高度膨胀而易使外层种皮破裂剥离。内层种皮较薄而光滑,细胞呈多边形,大小不一,层叠排列;二片胚乳肥厚,细胞呈立方或短棒状,排列整齐;子叶菲薄,细胞呈长方形或多边形,排列紧密,气孔丰富。常规生物电镜制样,一定程度上反映了吸水膨胀后的胖大海超微形态结构,其图像清晰,但易受结构破坏缺失而影响整体观察;而烘干加锇酸熏染电镜制样,能更好地保存干燥胖大海结构,同时可获得高质量图像,二者相辅相成,有助于较全面了解胖大海超微形态结构的特点。

Morphological characteristics of the Semen Sterculiae Lychnophera were examined by scanning electron microscope（ SEM） by using three different preparation techniques of SEM samples including drying directly,conventional method and Osmium tetroxide solution fumigation dyeing after drying. The effect of three treatments above was also analyzed. The results showed that the surface of the thin and fragile outer seed coat had irregular wrinkles,abundant glandular scales and stomatas and a few non-glandular hairs. The epidermal cells were polygonal. The parenchyma cells of the thicker middle layer seed coat were cluster which were crosslinked with each other. The leathery belt,leathery sieve pores,spiral vessels and annular vessels were distributed among the parenchyma cells. The middle layer seed coat expanded remarkably after water absorption and was easy to break the outer seed coat.The parenchyma cells with thin wall were ranged within various sizes and were easier to be broken. The pits and pit membrane were clear. The thin and smooth inner seed coat was composed of hierarchical polygonal cells. Two pieces of endosperm were hypertrophic and cubic or short-rop shaped cells arranged neatly. Cells of the thin cotyledons were rectangular or polygonal,which were closely packed and with abundant stomatas among them. To a certain extent,conventional biological EM sample preparation reflected the ultrastructure of the Semen Sterculiae Lychnophera after water swelling. The imagesobtained were clear,but damage or loss of the structure occurred easily and thus affected the overall view. Drying the sample which was dyed by osmium tetroxide solution fumigation could keep better structure of the Semen Sterculiae Lychnophera and obtain high quality images at the same time. Combined with these two methods was beneficial to understand the characteristics of seed ultrastructure more comprehensively.