CYTOSKELETON AND CYTOPLASMIC ORGANIZATION OF POLLEN AND POLLEN TUBES

The pollen grain and the pollen tube fulfill important functions in the sexual reproduction of higher plants. The pollen grain is concerned with conveying the two sperm cells or their progenitor, the generative cell, to the female gametophyte. The pollen tube serves as a guide and a pathway for the sperm cells on their course to the embryo sac so that they can complete double fertilization. This chapter focuses on the cytoskeleton of the vegetative cytoplasm of pollen grains and pollen tubes. The cytoskeleton is involved in numerous intracellular processes, such as organelle movement, organization of the cytoplasm, endocytosis and exocytosis, cytomorphogenesis, meiotic and mitotic division, and cell wall deposition. The distribution of calcium in pollen tubes is discussed in relationship to pollen tube growth, intracellular movement, and the activity of the cytoskeleton. The movements of the organelles and nuclei inside the pollen grain and the pollen tube are also described. © 1992 Academic Press Inc.