Ovary

Ovarium

Also known as: ovaries, female gonad

The paired almond-shaped female gonad on the lateral pelvic wall that stores the finite supply of oocytes, releases one at ovulation each cycle, and secretes estrogens, progesterone, inhibin and androgens.

Show on body map Female Reproductive Organs Hypothalamic–Pituitary Axis

Overview

Size≈3 × 2 × 1 cm

Follicle pool at menarche≈300 000–400 000

Oocytes ovulated per lifetime≈400–500

Each ovary measures about 3 × 2 × 1 cm in the reproductive years (smaller and wrinkled after menopause). It lies in the ovarian fossa on the lateral pelvic wall, a shallow depression bounded by the external iliac vessels in front and above, and the internal iliac vessels and ureter behind; the obturator nerve runs in the floor of the fossa, so ovarian disease can refer pain to the medial thigh.

The ovary hangs from the posterior layer of the broad ligament by a short fold, the mesovarium, through which vessels enter at the hilum. It is held by two further ligaments: the suspensory ligament of the ovary (infundibulopelvic ligament), carrying the ovarian vessels from the pelvic brim to its upper (tubal) pole, and the ovarian ligament, linking its lower (uterine) pole to the uterus. The ovary itself is not covered by peritoneum but by a simple cuboidal ovarian surface epithelium (historically misnamed "germinal epithelium"), beneath which lies a dense connective-tissue capsule, the tunica albuginea.

Internally, the cortex contains follicles at all stages of development embedded in a highly cellular stroma, and the medulla contains loose connective tissue, large spiral vessels, lymphatics and nerves, plus hilus cells (Leydig-cell-like). Because the ovary releases the oocyte into the peritoneal cavity, the female genital tract communicates with the peritoneum — a route for infection.

Location: Ovarian fossa on the lateral pelvic wall, attached to the posterior surface of the broad ligament; level of the pelvic brim, behind and below the uterine tube.

Parts & subdivisions

Cortex
Follicles (primordial to mature), corpora lutea and corpora albicantia in a dense cellular stroma.
Medulla
Loose connective tissue with spiral vessels and nerves.
Surface epithelium and tunica albuginea
Simple cuboidal mesothelium-derived covering over a dense collagenous capsule; possible origin (with fimbrial epithelium) of epithelial ovarian tumours.
Corpus luteum
Endocrine structure formed after ovulation.

Anatomy

Innervation: Ovarian plexus along the ovarian artery (sympathetic from ≈T10–T11, with visceral afferents) — pain referred to the periumbilical region; parasympathetic fibres from the pelvic splanchnic nerves.
Arterial supply: Ovarian artery (from the abdominal aorta at ≈L2), descending in the suspensory ligament and anastomosing within the broad ligament with the ovarian branch of the uterine artery.
Venous drainage: Pampiniform plexus → ovarian vein: right → inferior vena cava; left → left renal vein.
Lymphatic drainage: Along the ovarian vessels to the para-aortic (lumbar) nodes.
Relations: Lateral: parietal peritoneum of the ovarian fossa, obturator nerve and vessels. Anterior/superior: external iliac vessels; uterine tube arching over it. Posterior: ureter and internal iliac vessels. Medial: uterus (via the ovarian ligament) and loops of bowel; on the right, close to the appendix.
Histology: Cortex of spindle-shaped stromal cells with follicles; medulla of loose connective tissue; simple cuboidal surface epithelium.
Development: Gonadal ridge on the posterior abdominal wall colonised by primordial germ cells; descends to the pelvis guided by the gubernaculum (which becomes the ovarian and round ligaments) — hence its aortic blood supply and para-aortic lymph drainage.

Function

Oogenesis and folliculogenesis; ovulation of a secondary oocyte each cycle.
Secretion of estradiol (granulosa cells), progesterone (corpus luteum), inhibins A and B, AMH, androgens and relaxin.

Clinical significance

Ovarian cysts and torsion

Functional (follicular, corpus luteum) cysts are common and resolve; rupture or haemorrhage causes acute pain. An enlarged ovary may twist on its ligaments (adnexal torsion): sudden unilateral pain with vomiting — a surgical emergency.

Ovarian tumours

Epithelial tumours (≈90 % of malignancies; high-grade serous carcinoma often arises from the fimbrial end of the tube; BRCA mutations; CA-125) present late with bloating, early satiety and ascites, spreading transcoelomically over the peritoneum. Germ-cell tumours affect younger women — the mature cystic teratoma (dermoid cyst) is the commonest ovarian neoplasm of young women. Sex-cord–stromal tumours include granulosa-cell tumours (estrogen, inhibin) and fibromas (Meigs syndrome: ascites and pleural effusion). Krukenberg tumours are metastases, classically from gastric signet-ring carcinoma.

Polycystic ovary syndrome

Enlarged ovaries with many small antral follicles, anovulation and hyperandrogenism.

Test yourself

A woman has oligomenorrhoea and hirsutism; ultrasound shows 25 follicles in each ovary. Which statement about PCOS is correct?

Diagnosis requires all three Rotterdam criteria
Chronic anovulation exposes the endometrium to unopposed estrogen, increasing endometrial cancer risk
FSH is typically much higher than LH
Insulin sensitivity is usually increased

Answer: Chronic anovulation exposes the endometrium to unopposed estrogen, increasing endometrial cancer risk

PCOS needs two of three criteria (anovulation, hyperandrogenism, polycystic morphology). Without ovulation there is no progesterone to oppose estrogen, so endometrial hyperplasia and carcinoma risk rises. LH is often high relative to FSH, and insulin resistance is typical.