Menstrual cycle
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The menstrual cycle is a recurring sequence of hormonal, ovarian, and uterine changes in humans and some other primates. It begins on the first day of menstrual bleeding and continues until the start of the next menstrual period.
The ovarian cycle includes the follicular phase, ovulation, and the luteal phase. Follicle-stimulating hormone supports follicle development, rising oestrogen contributes to an LH surge, and the surge triggers ovulation. The corpus luteum then produces progesterone and oestrogen.
The uterine cycle includes menstrual, proliferative, and secretory phases. The endometrium is shed during menstruation, rebuilds under oestrogen, and becomes receptive to implantation under progesterone. If pregnancy does not occur, hormone levels fall and a new cycle begins.
Cycle length and symptoms vary among individuals and across the lifespan. The cycle is regulated through feedback among the hypothalamus, pituitary gland, ovaries, and reproductive tract and can be affected by age, health, nutrition, stress, medication, and endocrine conditions.
Source details and credits
- Source / publisher: Wikipedia
- URL type: WWW
- Credits: Wikipedia
- URL: https://en.wikipedia.org/wiki/Menstrual_cycle