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From Reproductive System
Female - Ovaries
Primary female reproductive organs that produce oocytes and hormones.
1. Overview
The ovaries are paired, almond-shaped organs in the female reproductive system responsible for producing oocytes (eggs) and secreting sex hormones such as estrogen and progesterone. As both endocrine and exocrine glands, they play a central role in ovulation, menstruation, and hormonal regulation of the reproductive cycle. The ovaries are also essential for female sexual development and fertility.
2. Location
The ovaries are located in the pelvic cavity, one on each side of the uterus. They lie posterior to the broad ligament and are attached to the lateral pelvic wall by the suspensory ligament of the ovary and to the uterus by the ovarian ligament. Each ovary is situated near the fimbriae of the fallopian tube, which captures the oocyte at ovulation.
3. Structure
Each ovary is approximately 3–5 cm long, 1.5–3 cm wide, and 1–1.5 cm thick in reproductive-aged women. Its structure includes:
Germinal epithelium: A thin outermost layer of cuboidal cells covering the ovary, continuous with the peritoneum.
Tunica albuginea: A dense connective tissue layer beneath the epithelium, providing structural support.
Cortex: The outer region containing numerous ovarian follicles in various stages of development, stromal cells, and corpus luteum or corpus albicans depending on the cycle phase.
Medulla: The central region composed of loose connective tissue, blood vessels, lymphatics, and nerves.
The ovary’s appearance and contents vary with age and menstrual phase. In postmenopausal women, the ovaries become smaller and fibrotic.
4. Function
The ovaries perform two key biological functions:
Gametogenesis: Production and maturation of oocytes through the process of oogenesis, culminating in ovulation each menstrual cycle.
Hormone secretion: Synthesis and release of sex hormones, primarily:
Estrogens: Promote development of secondary sexual characteristics and regulate the menstrual cycle.
Progesterone: Prepares the endometrium for implantation and supports early pregnancy.
Inhibin and relaxin: Regulate FSH secretion and aid in pregnancy-related changes.
5. Physiological Role(s)
The ovaries are central to female reproductive physiology:
Ovarian cycle: Each month, under the influence of FSH and LH from the anterior pituitary, follicles develop. One dominant follicle matures and ovulates, while the remainder undergo atresia.
Ovulation: Mid-cycle LH surge causes the mature (Graafian) follicle to rupture, releasing an oocyte into the fallopian tube.
Corpus luteum formation: The ruptured follicle transforms into the corpus luteum, which secretes progesterone to maintain the uterine lining for potential implantation.
Hormonal feedback loop: Ovarian hormones exert positive and negative feedback on the hypothalamic-pituitary-gonadal axis to regulate the menstrual cycle.
Puberty and menopause: Estrogen from the ovaries triggers puberty; eventual depletion of follicles leads to menopause and cessation of menstrual cycles.
6. Clinical Significance
Several disorders and clinical conditions affect the ovaries:
Polycystic Ovary Syndrome (PCOS): A hormonal disorder causing irregular ovulation, multiple small cysts, hyperandrogenism, and infertility. Often associated with insulin resistance.
Ovarian cysts: Fluid-filled sacs within the ovary, commonly functional (follicular or luteal) but sometimes pathological (e.g., dermoid cysts, endometriomas).
Ovarian torsion: Twisting of the ovary on its ligamentous supports, compromising blood flow. Presents as acute pelvic pain and requires emergency surgical intervention.
Ovarian cancer: A serious gynecologic malignancy, often detected late due to vague symptoms. Includes epithelial, germ cell, and stromal subtypes. Screening and early detection remain challenging.
Premature Ovarian Insufficiency (POI): Early depletion or dysfunction of follicles before age 40, leading to irregular menses or infertility.
Infertility: Conditions such as anovulation, diminished ovarian reserve, or luteal phase defects can impair fertility. Assessment includes hormone levels (FSH, LH, AMH), ultrasound, and ovulation tracking.
Ovarian hyperstimulation syndrome (OHSS): A risk of fertility treatments, involving swollen, painful ovaries and fluid imbalance due to excessive response to gonadotropins.
The ovaries are regularly evaluated through pelvic exams, transvaginal ultrasound, hormone testing, and surgical techniques like laparoscopy in gynecologic and fertility practice.
Did you know? The testes are located in the scrotum, outside the body, to maintain a temperature lower than the body’s temperature for sperm production.