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It originates after the initial meiotic division but before ovulation. As a result of this, it has a 2N haploid oocyte. The follicle is dominated by the massive follicular antrum. After the first meiotic division, the secondary oocyte is eccentrically implanted. Its limits are defined by the zona pellucida and the corona radiata, a multicellular layer. The ovum will have three layers as it escapes the Graafian follicle and enters the oviduct: oocyte, zona pellucida, and corona radiata.

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  graafian_follicle2