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| Gymnosperm Fertilization
In gymnosperms, the gametophyte stage is short-lived. The male gametes are microgametophytes and develop from microspores producing sperm cells. Megagametophytes or the female gametes develop from the megaspores and are present in the ovule. The female gametophyte produces multiple archegonia. Pollen grains are transferred between plants from pollen cone to the ovule through pollinators like wind or insects. Pollen grains enter into ovule through micropyle. The pollen grains mature inside the female gametophyte and produce sperm cells. Two modes of fertilization is seen in gymnosperms. In plants like Cycads and Ginkgo, sperms are motile and they swim directly into the egg inside the ovule. In plants like conifers and gnetophytes, the sperms have no flagella and they are passed on to the egg through the pollen tube. After fertilization, the resulting embryo develops in the female gametophyte and the ovule forms into a seed and a seed coat. This will become are new sporophyte which consists of two embryonic leaves. жүктеу/скачать 408,88 Kb. Достарыңызбен бөлісу:
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