Ultrastructural and autoradiographic study of Chara vulgaris Manubria

Ultrastructural changes of manubria of Chara vulgaris during spermiogenesis were studied. The changes (as compared to the antheridial filament proliferation stage) involve thickening of the content of secretive vesicles and changes in their consistency, the disappearance of rough endoplasmic reticulum (ER) and appearance of smooth ER, increases in the number and size of plastoglobules in plastids, condensation of mitochondria, and significant cell vacuolization. Autoradiography with 3H-fucose pulse incubation showed that during spermatogenesis it was incorporated into the manubria. Their radioactivity decreased after 2 h postincubation in nonradioactive fucose during spermiogenesis. This was not observed during proliferation of antheridial filament cells. It is suggested that polysaccharide secretion into the internal antheridial space increases during spermiogenesis, perhaps connected with the thickening of secretive vesicle content observed by electron microscopy.