Figure 1.

The microgametophyte of M. vestita at and after the time of imbibition. (a) At the time of imbibition, the male gametophyte of M. vestita consists of a single cell that is contained within the microspore wall. A large centrally positioned nucleus is surrounded by dozens of starch-containing plastids. (b) Spermiogenesis is initiated by placing the spore into an aqueous medium, and all of the development occurs within the spore wall. At 30–45 min after imbibition, there is a change in the organization of the cytoplasm: the plastids become aggregated along 1 side of the microspore and the nucleus becomes displaced toward the opposite side of the gametophyte. Images photographed with Phase Contrast optics. Bar = 25 μm.