二种固定方法对扫描电镜用植物细胞冷冻割断样品的影响

Effects of Two Fixatives on Freeze-fracture Specimen of Plant Cells for Scanning Electron Microscope

本文用冷冻割断法在扫描电镜下观察了大蒜(Allium sativum L.)根尖分生组织细胞内部的三维结构。样品制备采用了两种固定方法:冷冻割断前只用1％的锇酸固定的材料易在细胞质和细胞核之间断开;而先用Bouin‘s液固定,再用1％锇酸固定的材料易使细胞核被断开。据此认为前一固定法适于研究细胞质的内部结构(如细胞骨架纤维、线粒体、内质网等)及其三维分布关系;后一种固定法适于核内结构(染色质、核仁、核基质纤维)的三维图象的研究,特别是核仁纤维中心染色质的三维结构。

Three-dimensional structures of meristematie cells of Allium sativum L. prepared by freeze-fracture method were studied by SEM. Two fixation procedures were used in proparation of specimen. The cells were often fractured between cytoplasm and nucleus, when specimens were fixed in 1%Osmic acid alone before freeze-fracture. Whereas the nuclei were frequently fractured if specimens were fixed first in Bouin's fluid(Pi-cric acid saturated solution 75ml, Fermalin 25ml, Acetic acid 5ml)and then in 1%Osmic acid before freeze-fracture. The former fixation procedure is suitable for the study of the interior structures of cytoplasm such as cyloskeleton fibres, mitochondrion, endoplasmic reticulam, golgi body, and their three-dimensional topopro-phy. The latter fixation method is suitable for the study of interior structure of nucleus such as ehromatin, nu-cleli, nuclear matrix filaments and their three-dimensional architectures, especially the three-dimensional struc-tures of chromatin in fibrillar centr of the nucleolus.