EFFECTS OF HYPERTHERMIA (41.5-DEGREES) ON CHINESE-HAMSTER OVARY CELLS ANALYZED IN MITOSIS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 39  (6) , 1911-1918
Abstract
The mitotic cells from an asynchronous population of Chinese hamster ovary cells exposed to 41.5.degree. C for 7 h were examined by light microscopy and EM to determine if there were any morphological abnormalities related to cell death or lengthening of metaphase induced by hyperthermia [cancer therapy method]. All components of the mitotic apparatus were formed during exposure to heat, and the mitotic apparatus was functional as demonstrated by eventual cell division. Heat caused the nuclear envelope to reform precociously around the chromosomes except in the region of the kinetochores, and the nuclear envelope remained associated with the chromatids during segregation. The precocious reformation of the nuclear envelope may be responsible for the lengthening of metaphase. Cells undergoing mitosis during the heat treatment possessed large evaginations of the plasma membrane, and the ubiquitous cortical microfilaments were absent in the region of these evaginations. Possibly related to the membrane damage were osmotic changes resulting in swollen mitochondria observed in heated cells entering mitosis. Since hyperthermic damage to the plasma membrane-microfilament complex was not observed in interphase cells or in cells completing division but was morphologically expressed during mitosis, the thermal lability of the plasma membrane must increase as the cells enter mitosis.