Pollen sac

The pollen sac (pollensac), Stamen In anther pollen Cystic structure. That is Microsporangium .
Pollen sac
Each Anther There are usually 4 pollen sacs, but some Botany (e.g. Mallow Only 2 pollen sacs). The pollen sac originated on the four corners of the basic anther organization In a large nuclear capacity -- the meristematic cell height Sporogonium . The archesporial cell Periclinal Division The formation of the two outer layers. Cells The outer layer of cells called parietal cells, the inner cell called sporogenous cells. Parietal cells division , differentiation Fiber layer of anther wall and gradually formed in the pollen sac around Tapetum . The tapetum cells for two or more nuclei of pollen development is very important, its dysfunction, often make pollen could not lose normal development. Reproduction Effect。 Sporogenous cells continue to divide, the formation of a large number of Pollen mother cell ( The microspore mother cells ). After the pollen mother cell Meiosis , 4 Chromosome Halve the number of sub cells, thus forming 4 mononuclear Pollen ( microspore ). With the further development of the microspore formation with 1 Vegetative cells With 1 germ cell Or 1 vegetative cell and 2 sperm The mature pollen grains. The mature pollen, the pollen sac next to destroy each other, into a cavity. The pollen sac itself from cracking pollen . Anther dehiscence in a variety of ways: the most common is the two pollen sacs at the junction of the longitudinal cracking, said Crack Such as, The morning glory , Lily Some along the central horizontal; anther dehiscence, said Transverse crack Such as, Hibiscus , Hollyhock Some; The chamber The top of a small hole, said Poricidal dehiscence Such as, Cuckoo , Eggplant Some are formed on the side wall of anther; several small flap opened outwards, said 3-valved Such as, Camphor tree , Berberis .