Springer Online Journal Archives 1860-2000
Summary Variable aggregates, composed of tubules with a mean diameter of 19 nm, were found exclusively within polyploid nuclei of the midgut, Malpighian tubes, cyst cells, testis epithelium, and trophocytes ofGerris najas. The nuclear inclusions are always in direct contact with the nucleoplasm, and no other structures are associated with them. They appear most abundant within degenerating nuclei of the midgut surface epithelium, where they form paracrystalline bodies or spindle-shaped inclusions with tapered ends. Smaller fusiform inclusions occur in younger epithelial nuclei but not in the diploid nuclei of regenerative cells. In other tissues, mainly spindle-shaped inclusions can be observed, the longest (4.5 μm) in cyst cell nuclei. The mean diameter of the tubules determined from transverse sections, resembles that of cytoplasmic microtubules and was verified statistically. The inclusions within trophocyte nuclei failed to react with monoclonal anti-β-tubulin antibody, although the antibodies could penetrate the nuclei after extensive lysis of the cells.
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