Electron microscopy of the spindle in locally heated cells.
Individual living cells in metaphase were exposed to a steep temperature gradient by placing a microheater near one spindle pole. The cells were then fixed and the spindle was examined by electron microscopy. The structure of the warmer half-spindle differed from the cooler half-spindle in several ways. Kinetochore microtubules were nearly parallel in the warmer half-spindle but were divergent in the cooler. The total length of microtubules in the warmer half-spindle was 52 per cent greater and the number of kinetochore microtubules per kinetochore averaged 16 per cent higher than in the cooler half-spindle. The warmer half-spindle was longer than the cooler. These observations clearly demonstrate a locally enhanced assembly of microtubules in the warmer half-spindle. The electron microscope study makes still clearer the unusual character of chromosome movement in the differentially heated cells: the structure of the warmer half-spindle is hard to distinguish from that in normal cells, yet chromosome movement there is far slower than normal (Nicklas, 1979).
D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D002875:Chromosomes / Q000648:ultrastructure; D006110:Grasshoppers / Q000033:anatomy & histology; D006358:Hot Temperature; D008297:Male; D008854:Microscopy, Electron; D008870:Microtubules / Q000648:ultrastructure*; D008938:Mitosis; D013090:Spermatocytes / Q000648:ultrastructure*; D013094:Spermatozoa / Q000648:ultrastructure*