| Abstract: | SYNOPSIS. Nuclear structure and mitosis in Gonyaulax monilata were studied. Between the arms of the U-shaped interphase nucleus is a band of material which, it is suggested, is homologous with the “central body” of G. tamarensis. Histochemical studies of whole cells, extruded nuclei and Epon-embedded sections indicate that the band is composed at least in part of protein, phospholipid and possibly RNA. The chromosomes of interphase nuclei are attached to the ends of the band. The band is also attached to a proteinaceous, extra-chromosomal matrix which pervades the nucleus. Studies on material treated with trypsin indicate that the matrix may be a factor in maintaining chromosomal integrity and orientation and nuclear form. During mitosis the band acts as a point of attachment for the chromosomes, and appears to control anaphase and telophase movements. It is suggested that the band is a component of the mitotic apparatus in G. monilata. |
