The female gonads are called the ovaries. In this article, we will initially look at the basic function, location, components and clinical significance of the ovaries. The latter part of the article will cover the ligaments associated with the ovaries and their vasculature, lymphatic drainage and innervation.
In both the males and females, the gonads develop within the mesonephric ridge and descend through the abdomen. However, unlike the testes, the ovaries stop in the pelvis.
The ovaries are paired, oval organs attached to the posterior surface of the broad ligament of the uterus by the mesovarium (a fold of peritoneum, continuous with the outer surface of the ovaries).
Neurovascular structures enter the hilum of the ovary via the mesovarium.
The main functions of the ovaries are:
- To produce oocytes (female gametes) in preparation for fertilisation.
- To produce the sex steroid hormones oestrogen and progesterone, in response to pituitary gonadotrophins (LH and FSH).
Components of the Ovary
The ovary has three main histological features:
- Surface – formed by simple cuboidal epithelium (known as germinal epithelium). Underlying this layer is a dense connective tissue capsule.
- Cortex – comprised 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.
Fig 2 – Cross section of an ovary. Shows the three major components of the ovary. Also shows the follicles at various stages of development.
Clinical Relevance: Disorders of the Ovaries
Ovarian cysts are fluid-filled masses that may develop in the ovary. They are most commonly derived from ovarian follicles, reaching approximately 2-2.5 cm. Most ovarian cysts are benign and develop during a woman’s child-bearing years, however, some larger cysts may cause problems such as bleeding and pain and require surgical removal.
Polycystic ovaries are characterized by hormone dysfunction and multiple (over 10) ovarian cysts. It is associated with infertility.
Ovarian tumours are another serious disorder. The most common cancers arise from epithelial components or germ cells. 90% of ovarian cancers are derived from epithelium, these are termed ovarian adenocarcinomas. Most germ cell tumours are teratomas, which comprise cells from all 3 germ cell layers and are usually benign.
Two peritoneal ligaments attach to the ovary;
- Suspensory ligament of ovary – fold of peritoneum extending from the mesovarium to the pelvic wall. Contains neurovascular structures.
- Ligament of ovary – extends from the ovary to the fundus of the uterus. It then continues from the uterus to the connective tissue of the labium majus, as the round ligament of uterus.
The main arterial supply to the ovary is via the paired ovarian arteries. These arise directly from the abdominal aorta (inferior the renal arteries). There is also a contribution from the uterine arteries.
Venous drainage is achieved by paired ovarian veins. The left ovarian vein drains into the left renal vein, and the right ovarian vein drains directly into the inferior vena cava.
The ovaries receive sympathetic and parasympathetic innervation from the ovarian and uterine (pelvic) plexuses, respectively. The nerves reach the ovaries via the suspensory ligament of the ovary, to enter the ovary at the hilum.
Lymph from the ovaries drains into the para-aortic nodes.