The mitotic cycle : the cytoplasm and nucleus during interphase and mitosis / by Arthur Hughes.

  • Hughes, Arthur Frederick William, 1908-
Date:
1952
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: The mitotic cycle : the cytoplasm and nucleus during interphase and mitosis / by Arthur Hughes. Source: Wellcome Collection.

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    the interphase cell and the cytoplasm inwards, the granules become denser and occasional vacuoles are to be seen. Next to the nucleus is usually an area of darkish cytoplasm, the cytocentre or centrosphere. It is free of large granules, though its structure is not homogeneous; there may be some vacuoles within it. The distinction between this body and the surrounding cytoplasm is a variable one; sometimes there is almost a sharp boundary, in other cells the whole structure can easily be overlooked. Strangeways and Canti^ describe it as follows : 'The centrosphere is seen as a distinct area lying as a cap over one side of the nucleus and contains a number of faint granules or filaments'. In phase-contrast micrographs of malignant cells of a mouse sar¬ coma, Ludford and Smiles^^ have shown that here also the centro¬ sphere ranges in size and distinctness from cell to cell. It has no special absorption in the ultraviolet. Generally it consists of a finely granular mass, but occasionally within it these authors state that there is a suggestion of a canalicular system. They are doubtful whether this corresponds to the reticulate structure of impregnated preparations, because such an appearance within the central body of the living cell is but rarely seen. The centrosphere is clearly shown by dark-ground illumination in a photomicrograph of a rat heart fibroblast published by Ludford in 1935, who says that this body corresponds 'to the Golgi apparatus of silver and osmic impregnation preparations'. A continuous and lobulated body of impregnated material is seen by the side of the nucleus in cells of a hepatic epithelium in culture described by Richardson.^® Similar preparations of Hill^^ of chick osteoblasts show only a number of discrete impregnated granules near the nucleus, arranged so as to suggest that the cytocentre includes, or is closely sur¬ rounded by this osmophilic material.* Some recent investigations by Palade and Claude^^ have still further increased the probability that in the living cell the Golgi material is represented solely by globular elements, a view for which Baker^^ has already assembled much evidence. It appears, however, that in living cells of the pancreas, the Golgi bodies are in the form of'clear canals' (Bensley^^). Palade and Claude isolated cells from a number of mammalian and embryonic chick tissues. They found that their lipoid inclusions, unlike the mitochondria, were stable in form when the cells were suspended in various media; but that when ethyl alcohol was added thereto, these droplets within the cells began to swell and to form myelin figures, which 'duplicate faithfully the numerous and different forms ascribed at various times to the Golgi apparatus'. Experiments with model substances showed that a high proportion of phospholipines was necessary to give this effect. They then went on to inquire whether * Lasfargues and Di FineI® have recently shown by vital staining methods that the Golgi zone in cells in tissue culture is composed of granular elements. 21