Ultrastructural Changes in the Nuclear Envelope During Mitosis of Chinese Hamster Cells: A Proposed Mechanism of Nuclear Envelope Reformation

Publisher Website
Google Scholar
Abstract
Direct fixation with chrome-osmium of mitotic Chinese hamster cells revealed the presence, close to the chromatin and chromosomes, of 3 elements not made visible by double fixation with glutaraldehyde followed by osmium tetroxide: highly electron-dense material, granules, and microfibers. The highly electron-dense material was probably of nucleolar origin. The granular materials surrounded the entire chromatin mass in late prophase after the nuclear envelope (NE) had disappeared. In metaphase and early anaphase, the granules were distributed uniformly along the periphery of the chromosomes. Most granules disappeared in late anaphase before new NE formed. Microfibers organized in bundles appeared during dissolution of the NE in prophase and were in the region that had been occupied by the old NE. Similar microfibers were also present in late anaphase and early telophase where new NE was about to be formed. In prophase and early metaphase, small vesicles were among the perichromosomal granules. Such vesicles were scarcely detectable in metaphase but reappeared near the chromosomesin late anaphase and in early telophase in the regions where the NE was about to be formed. It is suggested that a portion of the granules and microfibers are residues of the old NE and might be partially reutilized in formation of new NE. A prominent feature in late anaphase and early telophase was the spatial association of mitochondria, vesicles, new NE, and chromatin in that order. It is suggested that mitochondria play an active role in formation of the vesicles which then coalesce to form the new NE.

This publication has 0 references indexed in Scilit: