The lamellar systems of cytoplasmic membranes in dividing spermatogenic cells by Drosophila virilis.

Abstract

Spermatogenic cells of Drosophila virilis were studied by light and electron microscopy. The persistence of a "nuclear wall" during the meiotic divisions has been reported by a number of early cytologists, but this interpretation has been a subject of debate. Electron micrographs of dividing spermatocytes reveal the presence of multiple layers of paired membranes surrounding the nuclear region. These lamellar membrane systems are not typical of the nuclear envelope, but were interpreted as such by light microscopists. The membranes constituting a pair are separated by an interspace of approximately 100 A and successive pairs are 200 to 400 A apart. These spacings are similar but not identical to those found in the lamellar systems of the Golgi complex. The cisternae of the endoplasmic reticulum in this material are devoid of attached ribonucleoprotein particles, are more precisely ordered than in vertebrate cells, and show a uniform, narrow intracisternal space of approximately 100 A. The conspicuous asters appear to be made up of similar paired membranes radiating from the centriolar region. The primary spermatocyte has numerous dictyosomes and a well developed endoplasmic reticulum in cisternal form, but no typical Golgi complex or endoplasmic reticulum is found during the meiotic division stages of metaphase to telophase. Evidence is presented that these cytoplasmic organelles contribute to the formation of the extensive lamellar systems that appear during meiosis. The results of the Golgi silver staining methods and staining tests for phospholipids, basophilia, and the PAS reaction, indicate that the lamellar arrays of membranes present during meiosis are indistinguishable from the Golgi complex in their tinctorial properties.