Three-dimensional observations on freeze-fractured frozen hydrated Papaver dubium pollen with cryo-scanning electron microscopy

The ultrastructure of generative cells and vegetative cells of Papaver dubium L. pollen was studied with low-temperature scanning electron microscopy (LTSEM). Liquid propane freezing resulted in a very fast fixation. The on-line fracturing and observation of the pollen grains was performed at — 130°C. The specimens were fully hydrated and did not undergo morphological changes during the procedure. Unfractured and cross fractured organelles, generative cells, vegetative nuclei and membranes are visible in three-dimensional images. The LTSEM micrographs show a lobed vegetative nucleus with many nuclear pores and a wrinkled generative cell in longitudinal direction. The vegetative nucleus and the generative cell are situated close to each other but structural connections are not observed.