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Fig. 1 | Reproductive Biology and Endocrinology

Fig. 1

From: A novel and compact review on the role of oxidative stress in female reproduction

Fig. 1

The development of ovarian follicles. Primary follicle: The center has an oocyte, and there is a flat layer of follicular cells on its periphery. Growing follicle: Including the primary growth follicle and secondary growth follicles. Primary growth follicle: One or more layers of cuboidal follicular cells between the egg cells, and follicular cells demonstrate red-stained zona pellucida, while the follicular periphery appears like connective tissue follicular membrane. Secondary growth follicle: Follicular cells appear in the follicular cavity, and some follicular cavities are large, forming a cumulus of oophores. Follicular cells are located on the inner wall of follicles and are arranged in layers, called granular layers. The follicular membrane includes the inner and outer membrane layers. Mature follicle: The follicle cavity is very large, and cumulus oophores are obvious. Follicular endometrial cells appear close to the follicular granule layer. There is a layer of basement membrane between the granule layer cells and follicular endometrial cells; endometrial cells are polygonal, with clear cytoplasm and round nuclei; cells can be seen between many capillaries, and outer membrane cells are located in the outermost layer, mostly spindle shaped with the surrounding connective tissue boundaries not obvious. Ovulation: Mature follicles develop to a certain stage, obviously protruding from the ovarian surface; with the follicular fluid increasing sharply, the pressure increases so that the prominent part of the ovarian tissue becomes thinner and finally ruptures; secondary oocytes and their peripheral zona pellucida and radiation crowns are discharged together with the follicular fluid. Empty follicle: At this time, the follicle is empty, indicating that the corpus luteum starts to form. Corpus luteum: The residual follicle wall collapses after ovulation; the connective tissue of the follicular membrane and capillaries stretches into the particle layer, and as the role of LH evolves, it evolves into a larger volume cell cluster, rich in capillaries and endocrine function and fresh yellow in color

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