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Overview of Female Reproductive Physiology
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Male and female external genitalia, arising from identical embryologic anlage, differentiate depending on the presence or absence of testosterone. Lack of the SRY gene (typically found on the Y chromosome) leads to development of ovaries, with subsequent maturation of female sex organs. The labia majora is a cognate of the scrotum and the clitoris and penis are similarly derived. Ambiguous genitalia occur when development and maturation occurs with a mixed genetic substrate or hormonal environment.
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The organs of the female reproductive system are the ovaries, ovarian ligaments, Fallopian tubes, uterus, vagina, vaginal and introital glands of Cowper and Bartholin, labia minora and majora, and the clitoris with its covering prepuce.
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The ovary usually cyclically matures one ovum within a follicle under the stimulation of follicle-stimulating hormone (FSH) from the pituitary. The developing follicle produces estrogen which causes proliferation of the endometrium. When the serum estrogen level reaches a threshold, a luteinizing hormone (LH) surge is triggered from the pituitary, effecting ovulation and formation of the corpus luteum that secretes increased levels of progesterone, inducing transformation of the endometrium from its proliferative to its secretory phase. The released ovum is captured by the fimbriated end of the Fallopian tube down which it travels to the uterine corpus. If fertilized in the tube or uterine cavity, the ovum may implant into the receptive endometrium establishing a pregnancy. If implantation does not occur, the corpus luteum involutes. When an ovulation cycle of estrogen and progesterone production is complete, the endometrium is sloughed as menstrual bleeding, and FSH again rises to stimulate development of another follicle. Implantation of a fertilized ovum leads to the development of the placenta, which secretes human chorionic gonadotropin (HCG), suppressing pituitary FSH and LH, leading to cessation of ovulation and menstruation.
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Anatomy of the Female Genitalia and Reproductive System
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At puberty, the mons pubis overlying the symphysis pubis (Fig. 11-1) becomes covered with hair, the female escutcheon. The hair forms an inverted triangle with a horizontal upper border. The male escutcheon is an upright triangle with the superior apex near the umbilicus.
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