The reproductive organ in a female animal in which the eggs are produced, and which may also produce hormones. Ovaries are typically paired, and release their eggs down oviducts or uterine tubes. In plants the hollow base of the carpel, containing the ovules, is termed the ovary. Its wall contributes to the fruit containing the seeds.
Mammalian ovary
Ovaries are part of the vertebrate female reproductive system. Normally, a female will have two ovaries, each performing two major functions: producing eggs, or (exocrine function) and secreting hormones, or (endocrine function).
As female mammals develop within the womb, each ovary develops a number of immature eggs associated with groups of other cells called follicles. While mammals were thought to develop their entire supply of eggs prenatally and soon after birth, new evidence from laboratory mice has called this into question, showing that female mice in fact produce new eggs throughout their reproductive lifetime. As the animal becomes reproductively mature (the process called puberty in humans), eggs will periodically mature and be released from the ovary (a process called ovulation) so that they will be available for fertilization by sperm.
Animal and human ovaries also produce various steroid and peptide hormones.
In humans, an egg launched from an ovary has to traverse a slight space before entering the fallopian tube and moving gradually down to the uterus. Ectopic pregnancy can also happen if a fertilized egg settles onto the cervix or onto the ovary itself, or if a fertilized egg passes through the gap between the ovary and the fallopian tube into the abdomen. If the egg fails to release from the follicle in the ovary an ovarian cyst may form.
Human anatomy
In the human 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. This end of the ovary is called the uterine extremity. The uterine tube (aka oviduct or fallopian tube) attachs to the ovary at the is tubal extremity. The ovaries are uncovered in the peritoneal cavity but are tethered to the body wall via the suspensory ligament. Each ovary receives blood from the ovarian (or gonadal) artery - which arises directly from the abdominal aorta - and the ovarian branch of the uterine artery that enters the ovary by way of the broad ligament and thus the mesovarium. The ovary (for a given side) is located in the lateral wall of the pelvis in a region called the ovarian fossa.
Ovaries are oval shaped and, in the human, measure approximately 3 cm x 1.5 cm x 1.5 cm. Functionally ovaries are involved in a number of processes: production of the female sex hormones (i.e., oestrogens and progesterone), storage and ovulation of the female gametes (oocytes) and formation of the corpus luteum to ensure regulation of the menstrual cycle and survival of the early embryo.
The adult ovary is a heterogeneous organ consisting of many cell types that lie in a dense collagenous extracellular matrix (ECM).
Extremities of the ovary
The end to which the uterine tube attach is called the tubal extremity. Also extending from this extremity are the ovarian artery and the ovarian vein, which are covered by a fold of peritoneum known as the suspensory ligament of the ovary.
Additional images
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Uterus and uterine tubes |
Uterus and right broad ligament, seen from behind. |
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