| 词汇 | megaspore |
| 释义 | BETA Examples of megasporemegaspore isn’t in the Cambridge Dictionary yet. You can help! As the functional megaspore, the megagametophyte is genetically identical to the egg cell. The nucellus is uniseriate, contains a thin-walled seed megaspore, and appears to be connected to the integument towards the chalaza only. No isolated megaspores were found associated with the sporophylls. The nucellus is poorly preserved but appears uniseriate, and is attached to the integument only at its base, and contains a thin-walled megaspore that lacks developed megagametophyte tissues. Within each ovule, a megaspore develops by mitosis into a megagametophyte. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The tetrasporic pattern is characterized by cell plates failing to form after either meiosis 1 or 2, and results in one four-nucleate megaspore. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Toward the center of each sorus and developing first are the megasporangia, each of which will produce a single large female megaspore. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. In gymnosperms, three of the four haploid spores produced in meiosis typically degenerate, leaving one surviving megaspore inside the nucellus. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. This megaspore becomes larger and the nucleus of it undergoes mitosis three times until there are eight nuclei. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. As with all seed-plants, the lyginopteridalean ovules had just one functional seed megaspore within the nucellus. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Only one is a functional megaspore whereas the others stay dysfunctional or degenerate. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. One kind, the megasporangium, produces only a single large spore (a megaspore). From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Within the seed coat, the megaspore develops into a tiny gametophyte, which in turn produces one or more egg cells. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Generally speaking, the megaspore, or large spore, germinates into a female gametophyte, which produces egg cells. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. This type of megagametophyte develops from the megaspore through three rounds of mitotic divisions. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The female gametophyte protrudes from the megaspore and bears a small number of archegonia, each containing a single egg. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Three cells die and one that is most distant from the micropyle develops into the megaspore. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The megagametophyte develops within the megaspore of extant seedless vascular plants and within the megasporangium in a cone or flower in seed plants. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The megaspore that remains divides mitotically and develops into the female gametophyte (megagametophyte) which eventually produces one or more eggs. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. |
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