EEB340H1 Lecture 17: EEB340 Lecture 17.docx
11 Apr 2012
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Document Summary
The spore is the first cell of the gametophyte generation in all land plants. Function of the gametophyte is to produce gametangia. Male gametophyte development is endosporic developing with in the spore wall (as in selaginella and water ferns) Prothallial cell equivalent to jacket cell. Antheridial initial divisions ultimately give rise to sperm initially divides into generative cell and tube cell. Male gametophyte has 3 cells very simple compared to other antheridia reduction. 4-celled male gametphyte at maturuity reduced gametophyte structure (male) Endothecium is one layer of sporangial wall. Megasporangium: eusporangiate in development, no endothecium, reduction in number of cells that will undergo meiosis, similar to selaginella, megaspore mother cell is buried deep in the sporangial wall. Megaspore undergoes free-nuclear divisions: no cell wall laid down when nucleus divides, enlarges in size because no sporopollenin wall, 100s free nuclei suspended in cytoplasm. Gametophyte development is endosporic end up with multicellular female gametophyte within the spore wall.
