Ultrastructure During Development of the Nucleus of Batophora Oerstedii (Chlorophyta; Dasycladaceae)1

SUMMARY The primary nucleus of Batophora oerstedii J. Agardh like that of the related Acetabularia, undergoes a great increase in size throughout vegetative development. Formation of small secondary nuclei represents an irreversible stage in the development of reproductive structures in the gametangia. Changes observed in the course of the life cycle include: i) an increase from 3 to 200 μm diam, of the nucleus; ii) increase in number of nucleoli; iii) development of the perinuclear region; iv) increased pore density in the nuclear membrane; v) development of chromosomes in the nucleoplasm; vi) formation of secondary nuclei; and, vii) division of secondary nuclei.