Overview
The ovaries are paired, ovoid-shaped intraperitoneal endocrine organs, found in the lower left and right abdominal quadrants. They function as the female gonads, thus playing a fundamental role in:
- Production of oocytes (female gametes) for reproduction
- Production of sex steroid hormones hormones (oestrogen and progesterone) – in response to pituitary gonadotropins (luteinising hormone and follicle-stimulating hormone)
Location & Size
Ovaries are very mobile but typically lie on the peritoneum of the pelvic wall within the ovarian fossa, close to the fallopian tubes. The fossa is formed between the angle of the external iliac artery and the internal iliac artery, on the obturator nerve. The bifurcation of the common iliac artery occurs at the level of the pelvic brim, anterior to the sacroiliac joint. The long axis of the ovary is oriented obliquely.
The normal ovary is 1.5 – 3 cm in length, 1.5 – 3 cm in width, and 1.0 – 2 cm in thickness (comparable to the size of a golf ball).
Histological Structure
- Surface – formed by simple cuboidal (germinal) epithelium, below which is a dense connective tissue capsule
- Cortex – composed of a connective tissue stroma and numerous ovarian follicles. Each follicle contains an oocyte, surrounded by a single layer of follicular cells.
- Medulla – formed by loose connective tissue and a rich neurovascular network which enters via the hilum of the ovary
Connections
Suspensory ligament of the ovary
- A fold of peritoneum extending from the mesovarium to the pelvic sidewall
- Carries the ovarian artery, ovarian vein, sympathetic and parasympathetic plexi
- Crosses over the external iliac vessels
Ovarian ligament
- Attached to the ovary inferiorly
- A continuation of the round ligament and attaches the ovary to the side of the uterus
- Round Ligament – The round ligament is a remnant of the embryonic gubernaculum. It originates at the uterine horns (where the fallopian tubes enter the uterus), and attaches to the labia majora, passing through the inguinal canal.
Broad ligament
- Ovaries are attached to the posterior lamina of the broad ligament by the mesovarium
Blood supply
The ovary has dual blood supply:
Ovarian artery
- Main arterial supply to the ovary
- Arises directly from the abdominal aorta, below the renal artery at the level of L2
- Runs through the suspensory ligament, to enter the hilum of the ovary via the mesovarium
- May anastomose with the uterine artery within the broad ligament
Uterine artery
- Ovarian branches from the uterine artery – branch of the anterior division of the internal iliac artery
Venous drainage
- The ovarian vein travels to the ovary by the suspensory ligament and provides drainage to the parametrium, cervix, mesosalpinx, and pampiniform plexus
- The right ovarian vein drains into the inferior vena cava
- The left ovarian vein drains into the left renal vein
- The ovarian veins may also anastomose with the para-ovarian, uterine, vesical, rectal, and vulvar venous plexuses.
Lymphatics
- Lymph drains via the ovarian vessels to the paraaortic nodes near the bifurcation of the renal arteries and the aorta (around level of L2).
- Lymph may also:
- Travel via lateral vessels to hypogastric nodes, which then drain into the para-aortic nodes
- Follows vessels close to the round ligament, leading to the external iliac and inguinal lymph nodes
Innervation
Sympathetic
- Ovarian plexus – originates in the renal plexus, and is carried by the suspensory ligament of the ovary to the enter the ovary at the hilum. Also innervates parts of the fundus of the uterus.
- Superior ovarian nerve – carried within the ovarian ligament
Parasympathetic
- Uterine (pelvic) plexus – arises from the pelvic splanchnic nerves.
Relations
Anteriorly
- Medial umbilical ligament
- Broad ligament
- Mesovarium
- Obliterate umbilical artery
Posteriorly
- Ureter
- Internal iliac vessels
- Suspensory ligament with neurovascular bundle
Superiorly
- Infundibulum of the uterine tube
- Suspensory (infundibulopelvic) ligament – the posterior extension of the broad ligament (mesovarium)
- External iliac vesssels
Inferiorly
Medially
- Ovarian ligament attaching ovaries to uterus
- Pararectal fossa
- Rectouterine pouch
- Bowel loops
Laterally
- Obturator vessels and nerves in ovarian fossa
- Obturator internus and fascia
- Parietal peritoneum of pelvic wall
Development
- Develop within the mesonephric ridge or intermediate mesoderm
- The ovaries will descend as they mature, however unlike their male counterparts, the testicles, the descent will end in the abdomen.
- The ovaries are attached to the gubernaculum, a strip of mesoderm.
- The other aspect of the gubernaculum connects to the uterus, preventing the ovaries from descending lower
- The proper ovarian ligament arises from the remnant of the gubernaculum
Anatomical Variants
- Suprapelvic position on psoas major muscle
- Inguinal canal location
- Spheroidal, flattened, crescentic shape
- Supernumerary ovaries
- Absence or hypoplasia of one or both ovaries
- Ectopic adrenal or thyroid tissue