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At birth, a female baby already has her lifetime supply of oocytes that will be released through ovulation when she is sexually matured, between menarche and menopause. Puberty initially starts with thelarche (breast budding) around the age of 11 and menarche usually starts at an average age of around 13. Initial cycles are anovulatory, but subsequently a single egg is released each cycle during a woman’s fertile years. The menopause is the end of menstrual cycles. Puberty, menstrual cycles, and establishment of pregnancy are controlled by the hypothalamic, pituitary, and ovarian hormones. Following the menopause, the ovaries are no longer able to produce enough oestrogen and ovarian failure results in a rise in the gonadotropins. |
