Follicular Atresia as a Proliferative and Inflammatory Event
Follicular atresia is more than a process of involution. It is also a proliferative event showing granulosa cells in mitosis and in transition into the interstitial cortical tissue in the different species studied. Meiosis is resumed in preantral and antral follicles, and cleavage occurs down to the morula stage. Leukocyte recruitment and capillary sprouting into the previous antrum of large antral follicles mimic a heavy inflammation as that seen in the preovulatory follicle. In analogy, granulosa cell subtypes with cytokeratin expression arise in the regressing follicle as in the preovulatory follicle. Follicular atresia, like ovulation, might depend on different degrees of oxidative stress and of danger signaling by innate immunity.
KeywordsGranulosa Cell Antral Follicle Preantral Follicle Preovulatory Follicle Follicular Atresia
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