Embryology of Flowering Plants Applied to Cytogenetic Studies on Meiosis

摘要: The life cycle of plants is constituted by two generations: sporophytic and gametophytic. Gametophytic generation the sexual generation. Differently from meiosis in animals, which gives rise to gametes, originates spores. Heterospory occurs some pterydophytes seed plants. This consists formation types spores separate sporangia (androsporangium gynosporangium). In angiosperms, when anther sporangia, are called androspores. When it seminal rudiment they gynospores. sporogenesis develops a complete endosporic manner. case gynospores formed, generally only one viable each sporangium. spore germinates and, after three mitotic divisions, forms female gametophyte, sporangium tissue nucellus. During development male first mitosis inside sporangium, other ones may occur gametophyte release. androgametophyte pollen grain gynogametophyte embryo sac. sperm cells formed second gametes. They present tricellular or generative during tube germination. gametes egg cell central cell. this way,