Fine Structure of Petunia Pollen Grain and Pollen Tube

Electron microscopic investigation of germinating Petunia pollen has yielded new data concerning fine structure of the pollen tube wall and of the protoplasm. The cell wall reveals two layers, an inner one containing cellulose microfibrils, embedded in a matrix, and an outer one consisting of acid resistant material. The multi-net growth theory is applicable to the growth of the pollen tube. Round the generative nucleus, there is a generative cytoplasm containing organelles. This cytoplasm is separated from the vegetative cytoplasm by a cell wall-like structure. So we ought to speak of a generative cell. The vegetative nucleus is lobed and is surrounded by a nuclear envelope containing pores. The Golgi apparatus produces vesicles which accumulate in the tip of the pollen tube and probably have a function in building up the cell wall.