Fig. 4

Live observation and sperm viability. a Bright field image of a sperm mass released from an antheridium, note that the tip cell of the antheridium is free of content due to cell rupture. b Bright field image of sperms. c Phase contrast image of sperms. Viable (d, e) and non-viable (f, g) sperms. Phase contrast (left) and fluorescence (right) images of the same view, non-viable sperms are stained with propidium iodide. Scale bars 50 µm in a; 10 µm in b, c; 20 µm in d–g