Electron microscope observations of nuclear evaginations in bronchial epithelium

Abstract

Evaginations or blebs involving both layers of the nuclear envelope were observed in ciliated columnar cells of the bronchial epithelium obtained from four patients during lobectomies. These are visible with the light microscope as supranuclear vacuoles. In adjacent sections electron micrographs showed the “vacules” to be bounded by “double membranes” identical in appearance to, and in some instances continuous, with the nuclear envelope. Nuclear components extend from the nucleus into the evagination. In some cells multiple evaginations extend in a row. These may be interconnected, or only the most proximal one may be continuous with the nucleus. In some evaginations, appearing at a distance from the nucleus and with no apparent attachment to it, breakdown of the enclosing envelope suggests the possible dissolution of the entire structure into the cytoplasm thus providing a means of transfer of nuclear material.