Nucleolar patterns in antheridial filaments of mono- and dioecious Chara spp. (Characeae) with different DNA C-values

Using NOR-silver-staining technique, nucleolar arrangements have been studied in antheridial filaments among 5 taxa of Chara with different genome sizes: monoecious Chara vulgaris L., C. fragilis Desv., C. contraria Kütz, and dioecious: Chara aspera Willd., and Chara tomentosa L. It is argued that due to a chain-series of regulatory processes establishing correlations between nucleolar cycles and consecutive cell growth cycles, the diminution of nucleoli observed throughout the development of antheridial filaments is a common and widespread feature of spermatogenesis shared by all the studied species. It is probably a controlling mechanism acting over the morphogenetic reduction of cell dimensions and cessation of mitotic divisions.