CELL DIVISION IN SPIROGYRA. I. MITOSIS.

摘要: Dividing cells of Spirogyra sp. were examined with both the light and electron microscopes. By preprophase many typical transverse wall micro-tubules disappeared while others seen in thickened cytoplasmic strands. Microtubules appeared polar cytoplasm at prophase by prometaphase they penetrated nucleus. They attached to chromosomes metaphase early anaphase, formed a sheath surrounding spindle during anaphase; interzonal strands telophase. The interphase nucleolus, containing 2 distinct zones chromatinlike material, fragmented prophase; anaphase nucleolar material coated chromosomes, obscuring them late anaphase. condensed nucleoplasm prophase, moving into nucleolus prometaphase. nuclear envelope was finally disrupted elongation; telophase membrane profiles reforming nuclei. During region contained vacuoles, few micro-tubules, sometimes eliminated n ucleolar material; most small organelles, including swollen endoplasmic reticulum tubular membranes, concentrated cytoplasm. Quantitative qualitative cytological observations strongly suggest movement intact rnicrotubules then back again