OvaryEdit
The ovary is a paired, almond-shaped gland that sits in the female pelvis as part of the broader reproductive system. It performs dual roles: the production of oocytes (gametes) and the synthesis of steroid hormones that regulate puberty, fertility, and many aspects of physiology. Each ovary contains a large reservoir of developing follicles, which comprise the ovarian germ cell lineage, and a stroma that supports hormonal production. The coordinated activity of the ovaries with the hypothalamus and pituitary gland drives the menstrual cycle and, in many individuals, the transition through menopause later in life. The ovaries operate in concert with other components of the female reproductive system to support reproduction and endocrine balance.
Structure and function
Anatomy
An ovary is enclosed by a dense outer layer called the tunica albuginea, beneath which lies the cortex—where follicles develop and hormones are synthesized. The medulla contains the loose connective tissue, blood vessels, and nerves that supply the organ. The delivery of blood is via the ovarian arteries, with venous drainage forming the pampiniform-like networks that assist in tissue perfusion. The hilum is the entry and exit point for vessels and nerves. For more about the surrounding framework, see ligaments of the pelvis and broad ligament.
Folliculogenesis
The functional units of the ovary are ovarian follicles, each containing an oocyte surrounded by granulosa and theca cells that coordinate hormonal responses. Folliculogenesis progresses from primordial follicles to primary, secondary (antral) follicles, culminating in a mature follicle ready for ovulation. The pool of primordial follicles is formed during fetal life and represents a finite resource that declines across the lifespan. The growth and maturation of follicles are tightly regulated by hormonal signaling, particularly at the interfaces of the hypothalamic-pituitary-gonadal axis and local ovarian signaling pathways. When a follicle reaches ovulatory maturity, a single oocyte is expelled in a process called ovulation, after which the remnants organize into a corpus luteum. The corpus luteum then secretes progesterone and estrogen to support the luteal phase and, if fertilization does not occur, regresses into a scar-like structure called the corpus albicans. See also corpus luteum and corpus albicans.
Hormone production
The ovary is an endocrine organ. The theca interna and granulosa cells collaborate to synthesize estrogens—predominantly estradiol in the reproductive years—and progesterone after ovulation. The balance of estrogens and progestogens shapes the menstrual cycle, the maturation of the endometrium, and secondary sexual characteristics. Other androgens produced by the ovary can be precursors for estrogen synthesis and contribute to libido and overall hormonal milieu. The major hormones produced in the ovary include estrogen and progesterone; for broader hormone context, see steroid hormone.
Blood supply and innervation
The ovary receives arterial blood from the ovarian arteries, with venous drainage through corresponding vessels. The organ’s innervation includes sympathetic and parasympathetic fibers that influence ovarian blood flow and follicular dynamics. The vascular and neural connections enable rapid endocrine signaling throughout the cycle and across the body.
Lifecycle and development
Embryonic and postnatal development
In embryos, the gonads begin as bipotential structures. In typical male development, the presence of the Y chromosome and the SRY gene drives testis formation, while in typical female development, the gonads differentiate toward ovaries under the absence of SRY signaling. Oocytes originate from primordial germ cells that migrate to the developing gonadal ridges and become oogonia, which then enter meiosis to form primary oocytes that arrest until puberty. The ovarian reserve—comprising primordial follicles—exists from birth and gradually depletes over the reproductive years.
Puberty to menopause
During puberty, rising gonadotropin signaling (as part of the hypothalamic-pituitary-gonadal axis) stimulates follicular growth and ovulation, establishing cyclical hormone patterns. Ovarian function typically remains robust into midlife, after which a gradual decline occurs, culminating in menopause—the end of ovarian follicular activity and perpetual loss of reproductive capability for many individuals. The timing and experience of menopause vary widely and are influenced by genetics, lifestyle, and health factors. See also menopause.
Clinical significance
Common disorders
Ovarian health is a central aspect of reproductive medicine and overall endocrine balance. Common conditions involve hormonal imbalance, cyst formation, and malignancy. Polycystic ovary syndrome (polycystic ovary syndrome) is characterized by anovulation in many cases, insulin resistance in some, and an array of metabolic and reproductive symptoms. Ovarian cysts, which can be functional or pathological, reflect cyclic ovarian activity and sometimes require clinical assessment. Ovarian cancer is a serious malignancy that can arise from different cell types within the ovary and often presents together with nonspecific symptoms; risk factors, screening, and treatment strategies are active areas of research and clinical practice. See also ovarian cancer and polycystic ovary syndrome.
Reproductive health and aging
Ovarian aging is a key component of female reproductive health. As the ovarian reserve declines with age, fertility typically decreases, and the hormonal milieu changes, contributing to menopause-associated symptoms and increased risk for certain conditions. Clinicians address these changes through a range of approaches, from hormonal therapies to lifestyle and medical management, always with attention to individualized risk profiles and patient goals. See also hormone replacement therapy and menopause.
Fertility technology and ethics
Advances in reproductive technology often involve the retrieval of oocytes for assisted reproduction, oocyte cryopreservation, and related treatments. These technologies intersect with ethical, legal, and social considerations that vary by jurisdiction and culture. See also in vitro fertilization and oocyte cryopreservation.
Comparative and evolutionary notes
Across mammals, the ovaries serve analogous roles with species-specific variations in timing, hormone signaling, and follicular dynamics. Studying different taxa sheds light on the evolution of reproductive strategies and the regulation of puberty and gestation. See also reproductive biology.