Ovaries

The ovaries are paired female gonads located within the pelvic cavity. They have two principal functions: production and maturation of female germ cells and secretion of reproductive hormones. Each ovary contains follicles at different stages of development within a specialized stromal framework.

Anatomically, the ovaries are closely related to the uterus, uterine tubes, broad ligament, pelvic wall, ovarian vessels, and ureters. Although they lie within the pelvis in adults, they develop high on the posterior abdominal wall and descend during fetal development. This embryological origin explains their arterial supply from the abdominal aorta and lymphatic drainage toward lumbar lymph nodes.

Location

The ovaries are located within the lesser pelvis, typically on either side of the uterus. Their precise position is variable and can change with age, pregnancy, parity, bladder filling, uterine position, and surrounding pelvic anatomy.

In individuals who have not undergone pregnancy, each ovary commonly lies near the lateral pelvic wall in a shallow depression called the ovarian fossa.

Ovarian Fossa

The ovarian fossa is a depression on the lateral wall of the pelvis associated with the usual position of the ovary.

Its anatomical relationships are important because major vessels, the ureter, and nerves lie near the ovary and can be relevant during pelvic surgery.

Shape and Size

The ovary is approximately almond-shaped in the reproductive years. Its size varies with age and physiological state, particularly with follicular development and pregnancy.

Before puberty the ovaries are relatively small. During reproductive life they become more active and develop an increasingly irregular surface as follicles mature and ovulation repeatedly disrupts the ovarian surface.

External Features

Each ovary is conventionally described as having:

• Two surfaces
• Two borders
• Two poles or extremities

These features provide a useful framework for understanding ovarian relationships and ligamentous attachments.

Medial and Lateral Surfaces

The ovary has medial and lateral surfaces. The lateral surface faces the pelvic wall, while the medial surface faces toward the pelvic cavity and is related to structures including the uterine tube.

The exact orientation of these surfaces can vary because the ovary is relatively mobile.

Anterior Border

The anterior border of the ovary is also called the mesovarian border. It is attached to the mesovarium and contains the ovarian hilum.

Blood vessels, lymphatics, and nerves enter and leave the ovary through this region.

Posterior Border

The posterior border is relatively free and is not attached to the mesovarium.

Its position and relationship to surrounding structures vary according to the orientation of the ovary within the pelvis.

Tubal Pole

The superior extremity of the ovary is commonly called the tubal pole. It lies near the infundibulum and fimbriae of the uterine tube.

The suspensory ligament of the ovary is attached in this region and carries the ovarian vessels, lymphatics, and nerves.

Uterine Pole

The inferior or uterine pole is directed toward the uterus and is connected to it by the ovarian ligament.

This ligament attaches near the lateral angle of the uterus, inferior to the uterine tube.

External Features of the Ovary

Feature	Description
Medial surface	Faces toward the pelvic cavity
Lateral surface	Faces the lateral pelvic wall
Anterior border	Attached to the mesovarium and contains the hilum
Posterior border	Free border
Tubal pole	Related to the uterine tube and suspensory ligament
Uterine pole	Attached to the uterus by the ovarian ligament

Ovarian Hilum

The hilum of the ovary lies along its anterior border where the mesovarium attaches.

Ovarian arteries, veins, lymphatic vessels, autonomic nerves, and connective tissue pass through this region.

Mesovarium

The mesovarium is a short peritoneal fold connecting the anterior border of the ovary to the posterior aspect of the broad ligament.

Unlike many intraperitoneal organs, most of the ovarian surface itself is not covered by typical peritoneal mesothelium. The mesovarium reaches the ovary at its hilum.

Broad Ligament

The broad ligament of the uterus is a double layer of peritoneum extending from the sides of the uterus toward the lateral pelvic walls.

The ovary is associated with the posterior aspect of the broad ligament through the mesovarium rather than lying enclosed within the broad ligament itself.

Ovarian Ligament

The ovarian ligament, also called the proper ligament of the ovary, connects the uterine pole of the ovary to the lateral aspect of the uterus.

It lies within the broad ligament and represents a derivative of the embryonic gubernaculum.

Suspensory Ligament of the Ovary

The suspensory ligament of the ovary, also called the infundibulopelvic ligament, is a peritoneal fold extending from the ovary toward the lateral pelvic wall.

It contains the ovarian vessels, lymphatics, and autonomic nerves and is therefore an important surgical landmark.

Ligaments and Peritoneal Attachments

Structure	Connection	Important Contents or Role
Mesovarium	Ovary to broad ligament	Provides route to ovarian hilum
Ovarian ligament	Ovary to uterus	Gubernacular derivative
Suspensory ligament	Ovary to lateral pelvic wall	Contains ovarian vessels, lymphatics, and nerves

Relationship to the Uterine Tube

The uterine tube lies close to the ovary, particularly near its tubal pole. The infundibulum of the uterine tube bears fimbriae that project toward the ovarian surface.

One fimbria, the ovarian fimbria, has a particularly close relationship with the ovary.

Ovulation and the Uterine Tube

The ovary is not directly continuous with the lumen of the uterine tube. During ovulation, the oocyte is released from the ovarian surface into the peritoneal cavity in the vicinity of the uterine tube.

Fimbrial movement and tubal fluid currents assist entry of the oocyte into the infundibulum.

Relationship to the Ureter

The ureter passes along the lateral pelvic wall and has an important anatomical relationship with the ovarian region.

This relationship is particularly relevant during surgery involving the ovary and ovarian vessels because injury to the ureter must be avoided.

Relationship to the External Iliac Vessels

The ovarian region is related to major pelvic vessels, including the external iliac vessels near the superior boundary of the ovarian fossa.

Knowledge of these relationships is important during surgical mobilization of the ovary and dissection near the lateral pelvic wall.

Surface of the Ovary

The ovarian surface is covered by a simple epithelial layer commonly called the ovarian surface epithelium. Historically, it was referred to as germinal epithelium, although it does not generate the female germ cells.

Beneath the surface epithelium lies a connective tissue layer called the tunica albuginea.

Tunica Albuginea

The tunica albuginea of the ovary is a thin layer of dense connective tissue immediately deep to the surface epithelium.

It is much thinner than the dense tunica albuginea surrounding the testis.

Internal Structure

The ovary is organized into an outer cortex and an inner medulla. These regions differ in their tissue composition and functional organization.

The cortex contains the ovarian follicles, while the medulla contains larger vessels, lymphatics, nerves, and loose connective tissue.

Ovarian Cortex

The ovarian cortex lies beneath the tunica albuginea and contains ovarian follicles embedded within specialized stromal tissue.

Follicles at different stages of development can be present simultaneously during reproductive life.

Ovarian Medulla

The ovarian medulla forms the deeper central region. It consists primarily of loose connective tissue containing large blood vessels, lymphatic vessels, and nerves.

The distinction between cortex and medulla is functional and histological rather than sharply demarcated by a capsule.

Cortex and Medulla

Region	Major Features
Cortex	Ovarian follicles, corpora lutea, corpora albicantia, and specialized stroma
Medulla	Larger vessels, lymphatics, nerves, and loose connective tissue

Ovarian Follicles

An ovarian follicle consists of an oocyte surrounded by specialized somatic cells. Follicles progress through a series of developmental stages during folliculogenesis.

Most follicles undergo atresia rather than reaching ovulation.

Primordial Follicles

Primordial follicles are the most immature follicles. Each contains a primary oocyte surrounded by a single layer of flattened follicular cells.

They are concentrated within the outer ovarian cortex and form the resting ovarian follicular reserve.

Primary Follicles

When a primordial follicle begins to develop, its follicular cells become cuboidal and proliferate, forming a primary follicle.

The surrounding cells differentiate into granulosa cells, and the zona pellucida develops around the enlarging oocyte.

Secondary Follicles

As follicular development continues, granulosa cells proliferate into multiple layers and the surrounding ovarian stroma differentiates into the thecal layers.

Fluid-filled spaces eventually appear among the granulosa cells and contribute to formation of the follicular antrum.

Antral Follicle

An antral follicle contains a fluid-filled cavity called the antrum. The oocyte becomes eccentrically positioned within a mound of granulosa cells.

Progressive enlargement of the antrum is a major feature of later follicular maturation.

Mature Follicle

A mature or preovulatory follicle becomes large and approaches the ovarian surface. The oocyte is surrounded by granulosa cells forming the cumulus oophorus and corona radiata.

At ovulation, the follicle ruptures and releases the oocyte with surrounding cells.

Granulosa Cells

Granulosa cells surround the developing oocyte and play important roles in follicular growth, endocrine signaling, and oocyte support.

They interact with the theca interna and participate in estrogen synthesis during follicular development.

Theca Interna

The theca interna develops from stromal cells surrounding the follicle. It is highly vascular and contains steroid-producing cells.

These cells produce androgen precursors that can be converted to estrogens by granulosa cells.

Theca Externa

The theca externa forms an outer fibrous layer around the developing follicle.

It blends with surrounding ovarian stromal connective tissue and provides structural support.

Zona Pellucida

The zona pellucida is a specialized extracellular glycoprotein layer surrounding the oocyte during follicular development.

It plays important roles in interactions between the oocyte and sperm during fertilization.

Corona Radiata

The corona radiata consists of granulosa cells immediately surrounding the zona pellucida of the oocyte.

These cells remain associated with the oocyte when it is released during ovulation.

Cumulus Oophorus

The cumulus oophorus is a mound of granulosa cells that projects into the follicular antrum and supports the oocyte.

The innermost cells of the cumulus form the corona radiata.

Ovulation

Ovulation is the release of an oocyte from a mature ovarian follicle. The follicle approaches the ovarian surface and ruptures, allowing the oocyte and surrounding corona radiata to enter the peritoneal cavity near the uterine tube.

The remaining follicular tissue subsequently reorganizes to form the corpus luteum.

Corpus Luteum

The corpus luteum is a temporary endocrine structure formed from the remnants of the ovulated follicle.

Granulosa and theca cells undergo luteinization and produce hormones, particularly progesterone, that support the endometrium.

Corpus Albicans

If the corpus luteum regresses, it is gradually replaced by fibrous connective tissue, producing a pale scar called the corpus albicans.

Repeated ovulation and subsequent healing contribute to the irregular surface appearance of ovaries during reproductive life.

Follicular Atresia

Follicular atresia is degeneration of ovarian follicles that do not complete maturation and ovulation.

Atresia can occur at multiple stages of follicular development and accounts for the loss of most follicles within the ovarian reserve.

Functional Structures of the Ovary

Structure	Principal Feature
Primordial follicle	Resting primary oocyte with flattened follicular cells
Developing follicle	Growing oocyte with proliferating granulosa and thecal cells
Mature follicle	Preovulatory follicle with large antrum
Corpus luteum	Temporary endocrine structure after ovulation
Corpus albicans	Fibrous remnant of a regressed corpus luteum

Arterial Supply

The principal arterial supply of the ovary comes from the ovarian artery, which arises directly from the abdominal aorta.

The ovarian artery descends retroperitoneally and enters the pelvis, reaching the ovary through the suspensory ligament.

Ovarian Artery

The ovarian artery usually arises from the anterolateral aspect of the abdominal aorta inferior to the renal arteries.

Its long course from the abdomen to the pelvis reflects the embryonic origin and descent of the ovary.

Ovarian Branch of the Uterine Artery

The ovary also receives blood through an ovarian branch of the uterine artery. This vessel approaches the ovary from the uterine side and anastomoses with branches of the ovarian artery.

The anastomosis provides collateral communication between the ovarian and uterine arterial systems.

Arterial Supply Overview

Artery	Origin	Route
Ovarian artery	Abdominal aorta	Reaches ovary through suspensory ligament
Ovarian branch of uterine artery	Uterine artery	Approaches from uterine side and anastomoses with ovarian artery

Venous Drainage

Venous blood leaves the ovary through a network of veins that form an ovarian venous plexus and ultimately the ovarian veins.

The right and left ovarian veins have different drainage patterns.

Right Ovarian Vein

The right ovarian vein typically drains directly into the inferior vena cava.

It ascends from the pelvis alongside the ovarian artery.

Left Ovarian Vein

The left ovarian vein typically drains into the left renal vein rather than directly into the inferior vena cava.

This asymmetry resembles the venous drainage pattern of the testes.

Venous Drainage Overview

Vein	Typical Drainage
Right ovarian vein	Inferior vena cava
Left ovarian vein	Left renal vein

Lymphatic Drainage

Ovarian lymphatic vessels accompany the ovarian blood vessels and ascend toward the posterior abdominal wall.

Lymph drains primarily into the lumbar lymph nodes, also called para-aortic nodes, near the origin of the ovarian arteries.

Why Ovarian Lymph Drains to Lumbar Nodes

The ovarian lymphatic pattern reflects the embryonic origin of the ovaries high on the posterior abdominal wall.

Although the ovaries later descend into the pelvis, their lymphatic connections remain associated with their original developmental location.

Innervation

The ovaries receive autonomic innervation through the ovarian plexus, which accompanies the ovarian vessels.

Additional autonomic connections occur through pelvic plexuses associated with the reproductive organs.

Ovarian Plexus

The ovarian plexus is derived from autonomic networks associated with the abdominal aorta and renal region.

Its fibers travel along the ovarian vessels toward the gonad.

Visceral Afferent Fibers

Visceral afferent fibers carrying pain from the ovary generally travel with sympathetic fibers toward spinal cord levels associated with the ovarian sympathetic supply.

This helps explain why ovarian pain can be perceived in lower abdominal rather than purely superficial perineal regions.

Embryological Development

The ovaries develop from the gonadal ridges on the posterior abdominal wall. Primordial germ cells migrate into the developing gonads and become incorporated into the ovarian tissue.

During ovarian differentiation, medullary sex cords regress while cortical cords develop and become associated with the female germ cells.

Primordial Germ Cells

Primordial germ cells migrate into the gonadal ridges during embryonic development. Within the developing ovary, they differentiate into oogonia.

Many oogonia enter meiosis during fetal life and become primary oocytes.

Primordial Follicle Formation

Primary oocytes become surrounded by flattened follicular cells, producing primordial follicles within the developing ovarian cortex.

These follicles establish the ovarian reserve that persists into postnatal life.

Ovarian Descent

The ovaries initially develop high on the posterior abdominal wall and later descend into the pelvis.

Their descent is limited by the developing uterus and the arrangement of the gubernaculum, preventing the extensive descent characteristic of the testes.

Gubernaculum

The embryonic gubernaculum connects the developing ovary with inferior structures. As the uterus develops, it becomes interposed along the gubernacular pathway.

The gubernaculum therefore becomes divided into two major adult derivatives.

Gubernacular Derivatives

Embryonic Portion	Adult Derivative
Between ovary and uterus	Ovarian ligament
Between uterus and labium majus	Round ligament of the uterus

Relationship to Müllerian Development

The ovaries and paramesonephric ducts have separate developmental origins. The ovaries arise from the gonadal ridges, while the uterine tubes, uterus, and cervix develop from the paramesonephric ducts.

This distinction explains why ovarian development can remain normal in some individuals with congenital Müllerian anomalies.

Age-Related Changes

The ovaries undergo substantial anatomical changes throughout life. Before puberty they are relatively small and contain numerous immature follicles.

During reproductive life, follicular maturation, ovulation, luteal formation, and atresia continuously alter ovarian morphology.

Postmenopausal Ovary

After menopause, depletion of the follicular reserve and loss of cyclic follicular activity result in progressive reduction in ovarian size and functional activity.

The ovarian stroma becomes relatively more prominent, and the surface may remain irregular because of previous ovulatory scarring.

Ovarian Torsion

Ovarian torsion occurs when the ovary rotates around its supporting vascular pedicle. This can compromise venous and lymphatic drainage and, with continued twisting, arterial inflow.

The suspensory ligament and ovarian ligament are important components of the anatomical axis around which torsion can occur.

Ovarian Cysts

Ovarian cysts are fluid-containing lesions arising within or from the ovary. Some are related to normal follicular or luteal physiology, while others arise from different ovarian tissues.

Large cystic lesions can alter ovarian position and increase mobility, potentially affecting the risk of torsion.

Follicular Cyst

A follicular cyst can develop when a follicle enlarges but does not undergo its usual sequence of ovulation and regression.

Such cysts arise from follicular structures within the ovarian cortex.

Corpus Luteum Cyst

A corpus luteum cyst can develop when fluid or blood accumulates within a corpus luteum.

Because the corpus luteum is highly vascular, hemorrhage can sometimes occur within or around the lesion.

Ovarian Hemorrhage

The ovary is highly vascular, particularly around developing follicles and corpora lutea. Rupture of ovarian vessels can result in hemorrhage into the ovary or peritoneal cavity.

The clinical significance depends on the amount of bleeding and the underlying cause.

Ovarian Masses and Lymphatic Spread

The lymphatic drainage of the ovary toward lumbar nodes is clinically important when evaluating the spread of ovarian disease.

This drainage differs from many other pelvic structures, which may drain primarily toward internal or external iliac lymph nodes.

Surgical Anatomy

Operations involving the ovary require careful attention to the ovarian vessels within the suspensory ligament, the ureter on the pelvic wall, the uterine vessels, and the attachments of the ovary.

The close relationship between these structures is particularly important when the ovarian vascular pedicle is divided or ligated.

Oophorectomy

Oophorectomy is surgical removal of an ovary. During the procedure, the vascular attachments within the suspensory ligament and connections to the uterus and broad ligament must be managed.

The nearby ureter is an important structure to identify and protect.

Imaging Anatomy

On pelvic ultrasound, the ovaries can often be recognized by the presence of multiple follicles within the ovarian parenchyma. Their size and appearance vary according to age and the phase of the reproductive cycle.

On cross-sectional imaging, their relationship to the uterus, ovarian vessels, pelvic sidewall, and surrounding bowel can assist identification.

Key Anatomical Relationships

• The ovaries are paired gonads located within the pelvis.
• Each ovary has medial and lateral surfaces, anterior and posterior borders, and tubal and uterine poles.
• The ovarian hilum lies along the anterior border.
• The mesovarium connects the ovary with the broad ligament.
• The ovarian ligament connects the ovary with the uterus.
• The suspensory ligament connects the ovarian region with the lateral pelvic wall and carries the ovarian vessels.
• The ovarian cortex contains follicles.
• The medulla contains larger blood vessels, lymphatics, nerves, and connective tissue.
• The ovarian artery arises directly from the abdominal aorta.
• The right ovarian vein usually drains into the inferior vena cava.
• The left ovarian vein usually drains into the left renal vein.
• Ovarian lymph drains primarily to lumbar lymph nodes.
• The ovaries develop from the gonadal ridges rather than the paramesonephric ducts.
• The ovarian ligament and round ligament of the uterus are derivatives of the gubernaculum.

Clinical Importance

The ovaries are clinically important because their location, mobility, vascular supply, and embryological origin influence the presentation and management of ovarian disease. Their relationship to the ureters and major pelvic vessels is particularly important during pelvic surgery.

The high abdominal origin of the ovaries explains why their arteries arise directly from the abdominal aorta and why their lymphatic drainage ascends toward lumbar nodes rather than remaining confined to pelvic lymph nodes.

The supporting ligaments are also important in ovarian torsion and surgery. The suspensory ligament contains the principal ovarian vascular pedicle, while the ovarian ligament connects the ovary to the uterus. Understanding these relationships provides the anatomical basis for interpreting ovarian imaging, pelvic operations, and patterns of disease spread.