THE FINE-STRUCTURE OF THE MALE GAMETE OF ECTOCARPUS-SILICULOSUS (ECTOCARPALES, PHAEOPHYCEAE) .1. GENERAL STRUCTURE OF THE CELL

The ultrastructure of male gametes of Ectocarpus siliculosus is descri bed and discussed in relation to the information available on other br own algal zoids. In general, the fine structure and the organelle asso ciations agree with those of other brown algal cells. In particular, t he male gametes typically contain a single chloroplast with a pyrenoid and a prominent concave eyespot, into which the swelling of the poste rior flagellum (the photoreceptor) fits. The continuity of the chlorop last endoplasmic reticulum and nuclear membrane, as well as the presen ce of a perinuclear Golgi consisting of several dictyosomes, is shown. The fine structure of microbodies, lipid bodies and different types o f vesicles, including physodes and coated vesicles, is also discussed. Several specializations of cellular elements and their interactions a re unique and have not been reported before. These features include th e connection between the nuclear envelope, the Golgi and the flagellar bases mediated by fibres resembling intermediate filaments, and the o rganization of the Golgi as well as the association of mitochondria an d a microtubular flagellar root.