Behavior of different gymnosperm pollen in the PD. (A–C)Ginkgo biloba pollen rapidly became submerged into the PD and entered the ovule upon PD withdrawal; (D)G. biloba pollen grains in the pollen chamber. (E–G)Cycas revoluta pollen also became submerged into the PD and entered the ovule. (H–J)Pinus thunbergii pollen entered PDs, but did not sink into the PD, remaining afloat at the top; (K)P. thunbergii pollen grains in the pollen chamber. (L–N)Abies firma pollen could enter PDs, but remained afloat at the top. O, ovule; P, pollen grains; Mi, micropyle; PC, pollen chamber. Scale bars = 200 μm.
Jin et al. BMC Plant Biology 2012 12:59 doi:10.1186/1471-2229-12-59