1998 Volume 63 Issue 3 Pages 293-300
To examine whether cytoplasmic rRNA are present at high density in the cytoplasm of generative and sperm cells (generative/sperm cells) in pollen grains of various plant species, in situ hybridization of 18S/25S rRNA was performed in thin sections of samples embedded in Technovit 7100 resin. The five plant species studied were Lilium longiflorum, Pharbitis nil, Silene latifolia, Pelargonium zonale and Plumbago auriculata. The timing and mode of pollen mitosis II (PM II) and the distribution of organelle nucleoids in generative/sperm cells differ in these species. In situ hybridization revealed that the density of rRNA was the same as or higher in generative/sperm cells than in vegetative cells, suggesting that the presence of rRNA in the generative/sperm cells at high density may be a general characteristic of mature pollen grains of various plant species.