OVERVIEW OF FEMALE REPRODUCTIVE PHYSIOLOGY
Male and female external genitalia arise from identical embryologic anlage. Phenotype development depends on the presence or absence of testosterone. Lack of the SRY gene (typically found on the Y chromosome) leads to development of ovaries and female sex organs. The female reproductive organs include the ovaries, ovarian ligaments, Fallopian tubes, uterus, vagina, vaginal and introital glands of Bartholin, labia minora and majora, and the clitoris with its covering prepuce. The labia majora and clitoris are cognates of the scrotum and penis respectively. Ambiguous genitalia reflect development and maturation from a mixed genetic substrate or hormone environment.
Pituitary follicle-stimulating hormone (FSH) cyclically stimulates the ovaries to mature one ovum within a follicle. The follicle produces estrogen causing endometrial proliferation. When the serum estrogen level reaches a threshold, a luteinizing hormone (LH) surge from the pituitary causes egg release and then the corpus luteum forms at the site of ovulation. The latter secretes progesterone which transforms the proliferating endometrium to its secretory phase. The released ovum, captured by the fimbriated end of the Fallopian tube, travels down the tube to the uterus. If fertilized, the ovum may implant into the receptive endometrium establishing a pregnancy. If implantation does not occur, the corpus luteum involutes after approximately 14 days and progesterone levels decline steeply. When an ovulation cycle is complete and the withdrawal of progesterone occurs, the endometrium sloughs as menstrual bleeding. FSH again rises stimulating development of another follicle. Implantation of a fertilized ovum leads to development of the trophoblastic cells which secretes human chorionic gonadotropin (HCG), which maintain the corpus luteum and suppresses pituitary FSH and LH and stopping ovulation and menstruation. Ultimately when the trophoblastic cells become a functional placenta, the corpus luteum will involute.
ANATOMY OF THE FEMALE GENITALIA AND REPRODUCTIVE SYSTEM
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.
Anatomy of the Uterus and Adnexa. A. Sagittal section of the female pelvis. Note the angle of the vagina with the vertical axis of the body, and the axis of the uterus perpendicular to the vaginal axis. The lips of the cervix are shown in the same plane as the anterior vaginal wall, which is shorter than the posterior wall. The rectovaginal pouch (cul-de-sac of Douglas) lies anterior to the rectal wall where it can be palpated during the rectal exam. The uterine fundus in the usual position is inaccessible to the rectal examining finger, but very close to palpation from the lower abdomen. B. View of the pelvis from above and in front. Note how the round ligament curves anteriorly and the uterine tubes curve posteriorly. C. Posterior view of the uterus and broad ligaments (spread out). Note the suspension of the ovary near the ...