Ultrastructure of mitosis and cytokinesis inZygnema sp. (Zygnematales, Chlorophyta)

摘要: Mitosis and cytokinesis have been studied in the green algaZygnema C. A. Agardh using interference-contrast light transmission electron microscopy. At prophase, nucleolus disintegrates numerous extranuclear microtubules near nuclear periphery penetrate into nucleoplasm. When aligned equatorial plane of open metaphase spindle chromosomes are coated with persistent nucleolar fragments. anaphase, vacuoles intrude interzonal region seemingly contribute to anaphase movement chromosomes. telophase, is reforming nuclei separated by cytoplasmic strands containing microtubules, interspersed vacuoles. Extensive bundles dictyosomes parallel, slightly inflated ER-profiles extend from poles telophase nucleus along longitudinal side chloroplast. Conceivably, these guide during its post-mitotic migration towards central interphase position between two halves dividing Throughout mitotic cycle, ubiquitous dictyosomes, positioned chloroplast core, seem very active. Arrays run may conduct dictyosome-vesicles cleavage plane. metaphase, septum growth becomes visible as an annular ingrowth plasmalemma. late or at entering interphase, extensive clump vesicles, associated appears leading edges advanced furrow. Apparent fusion vesicles head centripetally-growing furrow results completion. The pattern mitosis inZygnema compared that closely related algae.