تسجيل الدخول

تسجيل

Early Follicular Phase

المؤلف:  Wass, J. A. H., Arlt, W., & Semple, R. K. (Eds.).

المصدر:  Oxford Textbook of Endocrinology and Diabetes

الجزء والصفحة:  3rd edition , p1262

2026-10-26

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During early follicular phase, activin has a critical role with respect to an improvement in aromatase activity with parallel to FSH exposition and simultaneous inhibition of production of androgens. Activin has also a role in boosting the receptivity of FSH. According to imaging studies, recent theories of ovarian follicular recruitment proposed that there are two or more cohorts of antral follicles during the early phases of menstrual cycle (Figure 1). Of interest, whereas the dominant follicle develops from the final wave, other waves of cohorts do not produce an ovulatory follicle. Those findings suggest that Graafian follicle selection might be observed more than once during natural menstrual cycles rather than being once in the early follicular phase of the menstrual cycle, as mentioned earlier. The competency of corpus luteum also seems to be similar in women with two versus three waves or in women with major versus minor waves preceding the ovulatory wave. However, the appearance of second wave in the late luteal phase or early follicular phase, rather than in mid- luteal phase, facilitates the selection of a dominant follicle. The functional status of dominant follicles that develop during anovulatory waves preceding the ovulatory wave in women is not fully understood; but available data suggest that dominant follicles of anovulatory waves may exhibit different physiologic characteristics than dominant follicles of ovulatory waves in women.

Fig1. A schematic representation of a three- wave cycle. Each line represents growth and regression of a follicle. Adapted with permission from Baerwald AR, Adams GP, Pierson RA. Ovarian antral folliculogenesis during the human menstrual cycle: a review. Human reproduction update 2012;18:73– 91. Copyright © 2011, Oxford University Press.

In the follicular phase, there are substantial changes in the endometrium with respect to increased levels of oestrogen and enhanced receptivity. All components of the endometrium including glandular structures, stromal cells, and vascular tissues present proliferation. Two-thirds of its upper part constitutes the functional layer, the remaining inner part makes up the basal layer. According to imaging studies, an average of 5 mm increase is observed in the thickness of endometrium. Ciliogenesis is also initiated 7/ 8th day of the cycle.