Hematoxylin procedure for staining mature pollen grains in maize with dimethylsulfoxide as a clearing agent.

Observing nuclei of mature pollen grains in maize is extremely difficult because the starch granules surrounding the nuclei are deeply stained. The cytoplasm of hematoxylin stained pollen grains becomes clear when DMSO and gentle heating are used. By separating the staining and clearing processes, uniformly stained pollen grains were consistently obtained. Using this method, 2,000 pollen grains were examined and it was determined that 99.5% were in the normal tricellular state, while pentacellular pollen, bicellular pollen and pollen grains with two vegetative nuclei were observed in the remaining 0.5%.