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The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in females are analogous to testes in males in that they are both gonads and endocrine glands. Ovaries secrete both estrogen and progesterone. Estrogen is responsible for the appearance of secondary sex characteristics of females at puberty and for the maturation and maintenance of the reproductive organs in their mature functional state. Progesterone functions with estrogen by promoting menstrual cycle changes in the endometrium.
The ovary (for a given side) is located in the lateral wall of the pelvis in a region called the ovarian fossa. The fossa usually lies beneath the external iliac artery and in front of the ureter and the internal iliac artery. The ovaries are not attached to the outer layer of the uterus via the ovarian ligaments.
In humans the paired ovaries lie within the pelvic cavity, on either side of the uterus, to which they are attached via a fibrous cord called the ovarian ligament. The ovaries are tethered to the body wall via the suspensory ligament of the ovary. The part of the broad ligament of the uterus that covers the ovary is known as the mesovarium. Thus, the ovary is the only organ in the human body which is totally invaginated into the peritonium, making it the only intraperitoneal organ.
There are two extremities to the ovary, the tubal extremity and the uterine extremity. The tubal extremity is the
end to which the fallopian tube attaches via the infundibulopelvic. The uterine extremity points downward and is attached to the uterus via
the ovarian ligament.
The ovaries are the site of gamete (egg cell, oocyte) production. The
developing egg cell (or oocyte) grows within the environment provided by ovarian
follicles. Follicles are composed of different types and number of cells
according to their maturation stage, which can be determined by their size.
When oocyte maturation is completed, an LH surge secreted by the pituitary
gland stimulates follicle rupture and oocyte release.
This oocyte development and release process is referred
to as ovulation. The follicle remains functional and transforms into a corpus
luteum, which secretes progesterone to prepare the uterus for possible embryo implantation. Usually each ovary takes turns releasing eggs roughly every month. However, this alternating egg release is random. If there was a case where one ovary was absent or dysfunctional then the other ovary would continue providing eggs to be released.
Ovaries secrete estrogen, progesterone,
and testosterone. Estrogen is
responsible for the secondary sex characteristics of females at puberty. It is
also crucial for the maturation and maintenance of the mature and functional reproductive
organs. Progesterone prepares the uterus for pregnancy and the mammary glands
for lactation. The co-actions of progesterone and estrogen promote menstrual
cycle changes in the endometrium. In women, testosterone is important for the
development of muscle mass, muscle and bone strength, and for optimal energy
level. It also has a role in libido in women.