Gross Anatomy
Ovaries are the female pelvic reproductive organs responsible for the production of sex hormones. They are dull white structures consisting of dense fibrous tissue that house the ova. [1] They are paired organs located on either side of the uterus within the broad ligament below the uterine (fallopian) tubes. The ovary is located within the ovarian fossa, a space that is bound by the external iliac vessels, obliterated umbilical artery, and the ureter. The ovaries are responsible for housing and releasing ova, or eggs, necessary for reproduction.
Each ovary is connected to the uterus and pelvic wall by ligaments: [1, 2]
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Mesovarium - A fold of peritoneum that attaches the ovary to the broad ligament of the uterus
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Suspensory ligament - Extends from the ovary to the pelvic wall, containing blood vessels, nerves, and lymphatics that supply the ovary
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Utero-ovarian ligament - Connects the ovary to the lateral aspect of the uterus
The ovaries receive blood from the ovarian artery (a branch of the abdominal aorta, originating below the renal arteries) and are drained by ovarian veins. These veins emerge from the ovary as the pampiniform plexus. The right ovarian vein drains into the inferior vena cava, while the left drains into the left renal vein. Blood vessels enter through the hilum located at the medial surface of each ovary. [3]
At birth, a female has approximately 1-2 million eggs, but only 300 of these eggs will ever become mature and be released for the purpose of fertilization.
Anatomy of the ovaries is displayed in the images below.
The ovaries are small, oval-shaped, and grayish in color, with an uneven surface. The actual size of an ovary depends on the woman's age and hormonal status; the ovaries, covered by a modified peritoneum, are approximately 3-5 cm in length during childbearing years and become much smaller and then undergo atrophy once menopause occurs.
At birth, ovaries contain about 1-2 million primordial follicles. By puberty, this number decreases to around 300,000-400,000. After menopause, ovarian size decreases dramatically as hormone production ceases and follicles degenerate. [4]
A cross-section of the ovary reveals many cystic structures that vary in size. These structures represent ovarian follicles at different stages of development and degeneration. [5, 6, 7]
The Menstrual Cycle
Each month, the ovaries go through a series of stages, depending on stimulation by the anterior pituitary hormones: the follicle stimulating hormone (FSH) and the luteinizing hormone (LH). A typical female cycle lasts 28 days; however, this can range from 21-35 days. The ovarian cycle has two distinct phases: the follicular phase (days 1-14) and the luteal phase (days 14-28).
Follicular Phase (Days 1-14)
The follicular phase begins on the first day of menstruation (Day 1), during which FSH stimulates the growth of several primordial follicles in the ovaries. These follicles contain immature oocytes. As this phase progresses, one follicle typically becomes dominant, maturing into a Graafian follicle. This dominant follicle produces increasing amounts of estradiol, which plays a key role in preparing the endometrium for potential implantation and also provides negative feedback to reduce FSH levels, causing other nondominant follicles to degenerate. Around Day 14, a surge in LH triggered by high estradiol levels leads to ovulation, when the mature oocyte is released from the dominant follicle and captured by the fimbriae of the fallopian tube. [1, 8, 9]
Studies have shed light on the molecular mechanisms underlying follicular development. Research has highlighted the role of anti-Müllerian hormone (AMH) in regulating the sensitivity of follicles to FSH, thus influencing follicular recruitment and growth. [10]
Ovulation (Around Day 14)
Ovulation marks the transition between the follicular and luteal phases. The LH surge causes significant changes in the ovary, including rupture of the dominant follicle and release of the oocyte. The oocyte is then transported into the fallopian tube, where it may be fertilized if sperm are present. If fertilization does not occur, the oocyte degenerates within 24 hours. [1, 8]
Luteal Phase (Days 14-28)
Following ovulation, the ruptured follicle transforms into a structure called the corpus luteum, which secretes progesterone and smaller amounts of estrogen. These hormones maintain the endometrial lining in preparation for possible implantation of a fertilized egg. If fertilization does not occur, progesterone levels decline as the corpus luteum degenerates into a scar-like structure known as the corpus albicans. This hormonal drop triggers menstruation, marking the end of one cycle and the beginning of another. [1, 8]
Throughout both phases, hormonal feedback loops involving FSH, LH, estradiol, and progesterone tightly regulate the ovarian function. FSH promotes follicular development during the early follicular phase, while LH is crucial for ovulation and corpus luteum formation in the luteal phase. Estradiol dominates during the follicular phase, promoting endometrial growth and preparing for ovulation. Progesterone takes over in the luteal phase to support endometrial maturation for potential pregnancy. [1, 8]
Studies have suggested that some women experience multiple "waves" of follicular development within a single cycle. While most cycles involve one dominant follicle that ovulates mid-cycle, some women may have two or even three waves of antral follicles developing throughout their cycle. However, only one wave typically results in ovulation. [11]
Ovarian Ligament
Several paired ligaments support the ovaries.
The ovarian ligament, also called the utero-ovarian ligament, is a fibrous band that connects the ovary to the lateral side of the uterus, just below the origin of the fallopian tubes. It is a remnant of the embryonic gubernaculum and does not contain any blood vessels. This ligament primarily serves to anchor the ovary to the uterus but does not contribute to neurovascular supply. This ligament is composed predominantly of dense collagen fibers that provide strength and rigidity, minimizing excessive movement of the ovary during physical activity and changes in intra-abdominal pressure. [1, 2, 12]
The posterior portion of the broad ligament forms the mesovarium, which attaches to the hilum of the ovary. The mesovarium supports the ovary and serves as a conduit for its arterial, venous, and lymphatic supply. However, it does not cover the surface of the ovary itself. [1, 2, 12]
The suspensory ligament of the ovary (infundibular pelvic ligament) attaches the ovary to the pelvic sidewall. This larger structure plays a critical role in supporting the ovary by carrying essential neurovascular structures, including the ovarian artery, vein, nerve plexus, and lymphatic vessels. Additionally, it is closely associated with the infundibulum of the fallopian tubes, ensuring optimal alignment for the fimbriae to capture the ovum. [1, 2, 12]
The suspensory ligament contains both sympathetic and parasympathetic nerves along with blood vessels. Sympathetic innervation comes from the ovarian plexus, which originates from the renal plexus, while parasympathetic innervation arises from pelvic splanchnic nerves via the uterine (pelvic) plexus. [1]
The broad ligament is a double-layered fold of peritoneum that attaches to both sides of the uterus and extends laterally to cover other reproductive structures. It consists of three parts: [1]
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Mesometrium (surrounds most of the uterus)
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Mesosalpinx (encloses the fallopian tubes)
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Mesovarium (supports the ovaries)
The ovarian ligament, mesovarium, and suspensory ligament collectively ensure that ovaries are properly supported within their pelvic location while facilitating the blood flow, nerve supply, and lymphatic drainage essential for ovarian function. [1]
Blood Supply, Nerve Supply, and Lymph Drainage
Blood supply to the ovary is via the ovarian artery; both the right and left arteries originate directly from the descending aorta. The ovarian artery and vein enter and exit the ovary at the hilum. The left ovarian vein drains into the left renal vein, and the right ovarian vein empties directly into the inferior vena cava.
Nerve supply to the ovaries runs with the vasculature via the suspensory ligament of the ovary, entering the ovary at the hilum. Supply is through the ovarian, hypogastric, and aortic plexuses.
Lymph drainage of the ovary is primarily to the lateral aortic nodes; however, the iliac nodes are also involved.
Microscopic Anatomy
Cortex and Medulla
Histologically, the ovary has two main sections: the outer cortex and inner medulla. A germinal layer coats the entire ovary, made of cuboidal epithelial cells.
The cortex is where the follicles and oocytes are found at various stages of development and degeneration. The cortex is made of tightly packed connective tissue. The stroma of this cortical connective tissue is composed of spindle-shaped fibroblasts that respond to hormonal stimulation in a way different from that of other fibroblasts in the body. Studies have shown that the extracellular matrix (ECM) in the cortex plays a significant role in maintaining follicular quiescence. The cortical ECM is rich in collagen, creating a stiff environment that helps regulate follicle dormancy and activation. This mechanical environment is crucial for controlling follicle development as changes in ECM composition can influence follicular activation and growth. [13]
The medulla is where the ovarian vasculature is found and is primarily loose stromal tissue. [14] The medulla provides a more pliant environment than the cortex, allowing for follicle expansion and growth. This region also contains growing follicles, which are supported by the vascular network essential for nutrient supply. The medulla's structure supports dynamic tissue remodeling during each hormonal cycle, contributing to ovarian function throughout reproductive life. [15]
Ovarian Follicles
Ovarian follicles are found within the stroma of the ovarian cortex. A follicle consists of an oocyte surrounded by follicular cells called granulosa cells that play a critical role in oocyte development. Granulosa cells proliferate as follicles grow and secrete hormones such as estrogen. After ovulation, the remaining granulosa cells transform into luteal cells to form the corpus luteum, which secretes progesterone to support early pregnancy if fertilization occurs. [16]
Follicles progress through distinct stages — primordial, primary, secondary, and antral — culminating in ovulation if they mature fully. Primordial follicles are primarily located in the cortex, while growing follicles are found deeper in the medulla. The activation of primordial follicles is tightly regulated by signaling pathways such as PI3K/AKT/FOXO3, which control their dormancy and growth initiation. [16] If the follicle fails to release the egg, it undergoes degeneration.
Natural Variants
Turner Syndrome
Turner syndrome is a chromosomal anomaly that is characterized by the 45,X karyotype and occurs sporadically via paternal nondisjunction. Many mosaics of this syndrome exist, but typical manifestations include the absence or dysfunction of the ovaries with presence of the uterus, cervix, and vagina. Primary amenorrhea occurs, with absence of breast development. A typical diagnosis is made prior to puberty. The common physical characteristics of Turner syndrome include short stature, webbing of the neck, swelling of the hands and feet, short fourth metacarpal, and cubitus valgus. Cardiac abnormalities such as coarctation of the aorta and renal abnormalities are common.
Pathophysiological Variants
Ovarian Cysts
An ovarian cyst is the enlargement of either ovary beyond 5 cm in size, which is considered abnormal. Many different types of ovarian cysts exist, each classified as benign or malignant. The most common benign ovarian cysts in a premenopausal female are functional cysts, which are typically simple, clear, and nonseptated. The most common malignant ovarian cysts are epithelial carcinomas. The presence of an ovarian cyst can be detected on bimanual examination, and the diagnosis can be confirmed using an ultrasound evaluation.
Ovarian Torsion
Ovarian torsion is an ovarian cyst that has grown to the point that it turns over on itself, twisting the suspensory ligament of the ovary and cutting off blood supply. The typical presentation of a woman with ovarian torsion is intense, severe, sudden-onset pain in the right or left lower quadrant. Ultrasound evaluation reveals decreased or absent Doppler flow to the ovary on the affected side. The diagnosis of ovarian torsion warrants emergency surgery to reverse the torsion, hopefully in time to avoid necrosis of the tissue.
Ovarian Cancer
Ovarian cancer is detected physically in the same manner as an ovarian cyst, by bimanual or pelvic examination. Confirmation is then obtained using ultrasound and further workup, as necessary.
Ovarian carcinoma is suspected when an ultrasound examination shows characteristics such as complex, multiloculated, septated masses. The tumor marker CA-125 may be tested serologically, and an elevated level may support the diagnosis of ovarian cancer. This tumor marker is not always helpful as it can be elevated in noncancerous conditions such as endometriosis, peritonitis, pregnancy, and liver disease. Ovarian cancer is an aggressive disease that is often not detected until the late stages.
The impact of the practice of ovarian conservation and prophylactic risk reducing Bilateral Salpingo-oophorectomy on the risk of ovarian cancer is presented in the work of Dr Berek. [17]
Other Variants
Other variants include the following:
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Surgical absence
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Ovarian transposition (oophoropexy)
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Postradiation changes
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Changes due to metastatic disease
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Variations secondary to transgender procedures
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Ovaries, anterior view.
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Ovaries, sagittal view.
