Morphological and quantitative changes in the population of cell organelles during microsporogenesis of Gasteria verrucosa

The morphological changes in the nucleus and cell organelles of Gasteria during the development of the pollen mother cell into the ripe pollen are described and discussed. From the tetrad stage till after the first mitotic division the plastids contain electron transparent granules. The number of cristae in the mitochondria increases after the first mitotic division. When the pollen wall is formed the excretion of the Golgi vesicles’ content and the contact of the plasma membrane with the callose wall determine the template of the pollen wall pattern. The formation of the material for the bacula, followed by that of the tectum, and finally by that for the footlayer, takes place on the plasma membrane. The excretion of the fine fibrillar content of the Golgi vesicles proceeds till after the formation of the footlayer. The excreted material remains between the bacula. The quantitative approach revealed that during meiosis the number of cell organelles remains constant. However, an increase in number takes place first after the pollen mother cell stage and before leptotene, secondly after the first mitotic division. The data are compared with the previous results obtained with Pinus sylvestris (WlLLEMSE 1971a, b, c).