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Oogenesis:A Collaborative Effort |
How many cells does it take to make an oocyte?The task of oogenesis is to construct a large cell containing a large and complex dowry of resources for construction of the embryo before it can either make them on its own or obtain them from its environment. Organization is critical: Components may be spatially restricted to facilitate establishment of distinct embryonic regions. Review the timing of oogenesis and compare to that of the male. Remember: most of the events of oocyte differentiation occur during prophase I of meiosis. In the mammal, all oogonial decisions and transformation into oocytes are completed either before or shortly after birth. But, there is no oocyte growth until puberty. Then, cohorts of oocytes resume development during each cycle. (See Browder et al., Fig. 3.2) In some organisms, all stages of oogenesis can co-exist in the ovary (e.g. frogs).
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