title: Cellular autophagocytosis induced by X-irradiation and vinblastine. On the origin of the segregating membranes.
abstract: Autophagocytosis was induced in cultured, human glial cells by X-irradiation or exposure to vinblastine sulphate. A transmission electron microscopic investigation of the origin of the segregating membranes in the autophagic process was performed by labelling of endocytotic vacuoles and lysosomes with electron-dense marker particles (native and cationized ferritin, colloidal gold and thorium dioxide). Cytochemical demonstration of the lysosomal marker enzyme acid phosphatase and serial sectioning of the cells were also carried out. The majority of newly formed, double-membrane bounded autophagic vacuoles were devoid of markers for both lysosomes and endocytotic vacuoles. Moreover, no evidence of origin from the endoplasmic reticulum was found and the segregating membranes of this type of autophagic vacuoles were, by process of elimination, considered likely to be derived from Golgi vacuoles or, possibly, assembled de novo. Autophagy also appeared to be effected through an alternative pathway involving a lysosomal wrapping or microautophagic mechanism.
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects / Q000528:radiation effects*; D002460:Cell Line; D004705:Endocytosis / Q000187:drug effects / Q000528:radiation effects; D005293:Ferritins / Q000032:analysis; D006046:Gold; D006801:Humans; D008247:Lysosomes / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D009457:Neuroglia / Q000187:drug effects / Q000528:radiation effects* / Q000648:ultrastructure; D010587:Phagocytosis / Q000528:radiation effects*; D013911:Thorium Dioxide; D014617:Vacuoles / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D014747:Vinblastine / Q000494:pharmacology*
chemical_list: D014747:Vinblastine; D006046:Gold; D005293:Ferritins; D013911:Thorium Dioxide; D000135:Acid Phosphatase