Late prophase in stamen hair cells of Tradescantia virginiana. (1-3)The mitotic spindle grows rapidly on either side of the nucleus and as it expands, it actually compresses the chromatin mass. (4) Nuclear envelope breakdown has just occurred, and the chromatin mass is beginning to expand into the cytoplasmic space. Although it cannot be visualized in these micrographs, the spindle microtubules have begun to interact with the chromosomes. Take me back.