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Follicular phase diagram of hormones and their origins Follicle-stimulating hormone (FSH) is secreted by the anterior pituitary gland (Figure 2). FSH secretion begins to rise in the last few days of the previous menstrual cycle, [ 3 ] and is the highest and most important during the first week of the follicular phase [ 4 ] (Figure 1).
2.6 Late tertiary and preovulatory (the follicular phase of the menstrual cycle) ... (populations at puberty range from 25,000 to 1.5 million). [4]
Follicular phase 100 μg/day Insignificant 146 L/day 700–3600 pmol/L 250–1300 pg/mL Luteal phase 180 μg/day Insignificant 146 L/day 1100–7300 pmol/L 400–2600 pg/mL Progesterone: Follicular phase 2 mg/day 1.7 mg/day 2100 L/day 0.3–3 nmol/L 0.1–0.9 ng/mL Luteal phase 25 mg/day 24 mg/day 2100 L/day 19–45 nmol/L 6–14 ng/mL
Menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that makes pregnancy possible. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. The uterine cycle governs the preparation and maintenance of the lining of the ...
The follicular phase (or proliferative phase) is the phase of the menstrual cycle during which the ovarian follicles mature. The follicular phase lasts from the beginning of menstruation to the start of ovulation. [12] [13] For ovulation to be successful, the ovum must be supported by the corona radiata and cumulus oophorous granulosa cells. [14]
With the concomitant rise in inhibin B, FSH levels then decline in the late follicular phase. This seems to be critical in selecting only the most advanced follicle to proceed to ovulation. At the end of the luteal phase, there is a slight rise in FSH that seems to be of importance to start the next ovulatory cycle.
While the normal human menstrual cycle typically lasts 4 weeks (28 days, range 24–35 days) and consists of a follicular phase, ovulation, and a luteal phase followed by either menstruation or pregnancy, the anovulatory cycle has cycle lengths of varying degrees.
Polymenorrhea is usually caused by anovulation (failure to ovulate), an inadequate or short luteal phase, and/or a short follicular phase. [4] [3] [5] Polymenorrhea is common in puberty and adolescence due to the immaturity of the hypothalamic–pituitary–gonadal axis (HPG axis). [4]