A comparative study on the ultrastructure of cultured cells and protoplasts of soybean during cell division

Summary Cultured soybean cells recovered from a marked decrease in cell division 20 hours after removal of their cell walls with enzymes and exhibited sustained mitotic activity. Mitosis was essentially similar in both cultured cells and protoplasts. At prophase microtubules aggregated in a clear zone surrounding the nucleus prior to forming the spindle. During metaphase and anaphase chromosomal microtubules were attached to diffuse kinetochores and extended to broad spindle poles; few interzonal microtubules were evident. Considerable endoplasmic reticulum was present at the spindle poles throughout division and may contribute to the new nuclear envelope at telophase. A typical phragmoplast consisting of vesicles, overlapping microtubules and associated electron-dense material appeared earlier in the protoplasts and developed into a thicker cell plate than found in the cultured cells.Supported by the National Research Council of Canada, Grant A6304.