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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 266 (1991), S. 525-534 
    ISSN: 1432-0878
    Keywords: Cytoskeleton ; Microtubules ; Microfilaments ; Spermatogonia ; Testis ; Ephestia kuehniella (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Testis follicles of Lepidoptera contain a large somatic cell termed Verson's cell. The present study focuses on the structure of Verson's cells and neighbouring germ cells in the Mediterranean mealmoth, Ephestia kuehniella (Pyralidae), using electron microscopy, antitubulin immunofluorescence, and phalloidin incubation for the visualization of microfilaments. Verson's cells of young larvae are connected with the follicle boundary and show large areas containing packages of glycogen particles, whereas Verson's cells of pupae lie freely within the testis follicle and are largely devoid of glycogen. Both developmental stages of Verson's cells have in common the presence of a dense cytoplasmic network of microtubules. A juxtanuclear subset of the cytoplasmic microtubule array is recognized by an antibody against acetylated microtubules. This indicates that more stable microtubules exist in this region. Microfilaments are arranged parallel to the cytoplasmic microtubules. The microtubule-microfilament-complex forms a cytoskeleton that may keep larger organelles, such as mitochondria and lysosomes, in a juxtanuclear position. Chromatin within the nuclei of Verson's cells is largely decondensed and nuclear pores are abundant. This indicates a high synthetic activity within the cells. The development of cells directly attached to Verson's cells, viz. prespermatogonia, may be controlled by the Verson's cells. Prespermatogonia, which differ in cytoplasmic density from spermatogonia further away from Verson's cells, may represent stem cells that give rise to spermatogonia and somatic cyst cells upon detachment from Verson's cells. This suggestion is compatible with the low division rate of prespermatogonia.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1040-452X
    Keywords: Chromatin ; Histone acetylation ; Testis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The structure of elongated spermatid nuclei was examined in the fly Megaselia scalaris using indirect immunofluorescence with anti-histone antibodies, scanning electron microscopy, and in situ hybridization with a centromere-specific oligonucleotide. The immunofluorescence experiments showed that, in keeping with the situation in most animals, histones are hyperacetylated prior to their displacement from the nucleus in the course of spermiogenesis. Scanning electron microscopy revealed that grooves run parallel to the long axis of the spermatid nuclei. The chromatin is segmented into blocks lateral to the grooves. This finding most probably indicates that the chromatin is not yet maximally condensed at this stage. The retarded chromatin condensation may be correlated with the export of somatic histones from the nucleus. The location of the centromeres could not be identified using scanning electron microscopy, but in situ hybridization showed that a centromere-specific oligonucleotide mapped to the central or close to the central areas within the spermatid nucleus. Possibly, the chromosomes are extended and arranged parallel to the long axis of the spermatid nucleus. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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