Ovaries: Anatomy, Function, and Disorders
The ovaries are the female reproductive organs that produce eggs, or ova, and hormones, mainly oestrogen, progesterone, and androgens. They are located on either side of the uterus and are about the size and shape of an almond.
They release an egg around the middle of the menstrual cycle in a process called ovulation. They also regulate the reproductive tract, the mammary glands, and the menstrual cycle through feedback mechanisms with the pituitary gland.
Anatomy of the Ovaries
The ovaries have two main parts: the cortex and the medulla. The cortex is the outer part that contains the ovarian follicles, which are small sacs that hold the immature eggs. The medulla is the inner part that contains blood vessels, nerves, and connective tissue. The ovaries are surrounded by a fibrous capsule called the tunica albuginea, which is covered by a layer of cuboidal epithelium.
The ovaries are held in place by several ligaments that attach them to the uterus and the pelvic wall. The main ligaments are the ovarian ligament, which connects the ovary to the uterus; the suspensory ligament, which attaches the ovary to the pelvic wall and carries the ovarian vessels and nerves; and the mesovarium, which is part of the broad ligament that supports the ovary and the fallopian tube.
Function of the Ovaries
The ovaries have two main reproductive functions in the body. They produce oocytes (eggs) for fertilisation and they produce the reproductive hormones, oestrogen, progesterone, and androgens.
The production of oocytes is controlled by hormones released by the hypothalamus and the pituitary gland in the brain. The hypothalamus secretes gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These hormones act on the ovaries to trigger the growth and maturation of a follicle, which is a small sac that contains an egg.
During the first half of the menstrual cycle, known as the follicular phase, FSH stimulates the development of several follicles in the ovaries. However, only one of them will become dominant and continue to grow, while the others will degenerate. The dominant follicle produces oestrogen, which helps to thicken the lining of the uterus (endometrium) and creates a favourable environment for a fertilised egg.
Around the middle of the cycle, usually between day 11 and day 21, the oestrogen level reaches a peak and triggers a surge of LH. This causes the dominant follicle to rupture and release the egg into the fallopian tube. This is ovulation. The egg can survive for 12 to 24 hours after ovulation, and it can be fertilised by sperm during this time.
After ovulation, the ruptured follicle transforms into a structure called the corpus luteum, which produces progesterone. This hormone maintains the endometrium and prevents further ovulation. If the egg is not fertilised, the corpus luteum degenerates, and the progesterone level drops. This leads to the shedding of the endometrium and the onset of menstrual bleeding, marking the end of the cycle.
Functions of Hormones Produced by The Ovaries
The production of hormones is also influenced by the feedback mechanisms between the ovaries and the pituitary gland. oestrogen and progesterone have different effects on the secretion of GnRH, FSH, and LH, depending on the phase of the cycle.
oestrogen can have a positive feedback effect, stimulating the release of more GnRH, FSH, and LH, or a negative feedback effect, inhibiting the release of these hormones. Progesterone usually has a negative feedback effect, suppressing the release of GnRH, FSH, and LH.
The hormones produced by the ovaries play an important role in reproductive development and function. Oestrogen is responsible for the development of secondary sex characteristics, such as breast growth, pubic hair, and fat distribution.
It also regulates the menstrual cycle, the reproductive tract, the mammary glands, and the bone density. Progesterone prepares the uterus for pregnancy, supports the implantation and development of the embryo, and prevents contractions of the uterus. Androgens, such as testosterone, are also produced by the ovaries in small amounts. They contribute to the growth of muscle mass, bone mass, and libido.
Disorders of the Ovaries
The ovaries are also susceptible to infections and diseases, such as ovarian cysts, polycystic ovary syndrome, ovarian cancer, primary ovarian insufficiency, and ovarian torsion. These conditions can affect the function and health of the ovaries and cause various symptoms and complications.
- Ovarian cysts are fluid-filled sacs that develop in or on the ovaries. They are usually benign and harmless, but they can sometimes cause pain, bleeding, or rupture. They can also interfere with ovulation and fertility. Ovarian cysts can be diagnosed by ultrasound and treated by medication or surgery, depending on the size, type, and symptoms of the cysts.
- Polycystic ovary syndrome (PCOS) is a hormonal disorder that affects the ovaries and other parts of the endocrine system. It is characterised by irregular or absent periods, excess androgen production, insulin resistance, and multiple cysts on the ovaries. PCOS can cause infertility, obesity, acne, hirsutism, and metabolic syndrome. PCOS can be diagnosed by blood tests, ultrasound, and physical examination. It can be treated by lifestyle changes, medication, or surgery, depending on the severity and goals of the patient.
- Ovarian cancer is a malignant tumour that originates from the cells of the ovaries. It is one of the most common and deadly cancers among women worldwide. It often has no symptoms in the early stages, but it can cause abdominal pain, bloating, weight loss, and abnormal bleeding in the later stages. Ovarian cancer can be diagnosed by blood tests, imaging tests, and biopsy. It can be treated by surgery, chemotherapy, radiation, or targeted therapy, depending on the stage and type of the cancer.
- Primary ovarian insufficiency (POI) is a condition in which the ovaries stop functioning normally before the age of 40. It causes irregular or absent periods, low oestrogen levels, and infertility. POI can be caused by genetic, autoimmune, or environmental factors. It can be diagnosed by blood tests and physical examination. It can be treated by hormone replacement therapy, fertility treatments, and psychological support.
- Ovarian torsion is a rare but serious condition in which the ovary twists around its ligament, cutting off its blood supply. It causes sudden and severe pain in the lower abdomen, nausea, vomiting, and fever. Ovarian torsion can be caused by ovarian cysts, pregnancy, or trauma. It can be diagnosed by ultrasound and physical examination. It can be treated by surgery to untwist or remove the ovary.
Conclusion
The ovaries are an essential organ that plays a key role in reproduction, menstruation, and hormonal balance. They are responsible for producing eggs and hormones that affect the female body and mind. They are also vulnerable to various disorders that can impair their function and health. It is important to take care of the ovaries by having regular check-ups, screening tests, and treatments when needed.
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