The Arrangement of Microtubules in Mitotic Cells of Spirogyra.

The distribution patterns of microtubules (MTs) in the mitotic cells of Spirogyra were examined by immunofluorescence microscopy. Some of the cortical MTs and MT-fibrils in the cytoplasmic strands at interphase seemed to be organized into MT-belts at prophase. The MT-belts fused side by side, decreased in length and developed into spindle-MTs at metaphase. During polar separation at anaphase, the shape and size of the half-spindles remained almost unchanged. Considerable amounts of polar MTs were seen between the two separating half-spindles. It seems possible that these polar MTs, which could consist of pairs of antiparallel MTs, might push the poles apart by a sliding mechanism.