Ovary - Diagram, Anatomy, Structure and Functions

Ovary: The ovary is an essential organ in the female reproductive system. It is responsible for generating eggs and producing vital hormones. The ovary comprises an outer cortex and an inner medulla, which contain specialized units known as ovarian follicles, where eggs mature. During a process termed folliculogenesis, these follicles progress to release eggs during ovulation.

Ovary Diagram

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Anatomy of the Ovary

Mammary Glands

External Structure

1. Location within the Female Reproductive System: The ovary is positioned in the pelvic cavity on either side of the uterus. It is attached to the back of the broad ligament of the uterus via the mesovarium and linked to the uterus by the ovarian ligament.
2. Size and Shape: The ovary's size and shape can vary among individuals and change over a woman's life. Usually, it is about 2-4 cm long and has a shape resembling an almond. However, these dimensions can fluctuate based on factors like age, hormones, and reproductive status.

Okazaki Fragments

Internal Structure

1. Ovarian Cortex and Medulla : The ovary is divided into two main parts: the outer cortex and the inner medulla. The cortex contains ovarian follicles, which are crucial for egg development. The medulla, located deeper, consists of connective tissue, blood vessels, and lymphatic vessels.
2. Ovarian Follicles : Ovarian follicles are specialized structures within the cortex that nurture developing eggs. Each follicle consists of an immature egg surrounded by supportive cells. These follicles progress through stages called folliculogenesis, leading to the release of a mature egg during ovulation.
3. Ovarian Stroma : The ovarian stroma is the supportive tissue surrounding the follicles, providing structural support to the ovary. It includes connective tissue, blood vessels, and lymphatic vessels, which supply nutrients and oxygen to the developing follicles.
4. Blood and Lymphatic Vessels : The ovary is highly vascularized, meaning it has an extensive network of blood vessels supplying nutrients and oxygen to the ovarian tissue. Lymphatic vessels also play a role in immune function and fluid drainage within the ovary.

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Functions of Ovary

Production of Oocytes (Eggs)

1. Oogenesis : Oogenesis refers to the process of egg development within the ovary. It starts before birth and continues throughout a woman's reproductive life. It involves the transformation of precursor cells called oogonia into mature eggs or ova.
2. Folliculogenesis : Folliculogenesis is the process of ovarian follicle development and maturation. Ovarian follicles are specialized structures containing immature eggs surrounded by supporting cells. Each month, several follicles begin to develop, but usually, only one fully matures and releases its egg during ovulation.

Systole and Diastole

Hormone Production

1. Estrogen : Estrogen is a hormone primarily produced by the ovarian follicles. It plays a vital role in developing secondary sexual characteristics and regulating the menstrual cycle. Estrogen promotes the growth of the uterine lining, preparing it for potential pregnancy.
2. Progesterone : Progesterone is produced mainly by the corpus luteum. It formed from the remnants of the follicle after ovulation. Progesterone supports the thickened uterine lining during the second half of the menstrual cycle (luteal phase) and prepares the uterus for embryo implantation and pregnancy.
3. Androgens : Androgens, including testosterone, are hormones produced in small amounts by the ovaries. They contribute to various aspects of female reproductive function, such as libido and ovarian regulation.

Sexual Reproduction in Flowering Plants

Role of Ovary in the Menstrual Cycle

1. Follicular Phase : The follicular phase marks the beginning of the menstrual cycle, characterized by the development of ovarian follicles under the influence of follicle-stimulating hormone (FSH). Estrogen produced by the growing follicles stimulates the thickening of the uterine lining.
2. Ovulation : Ovulation occurs around the middle of the menstrual cycle, triggered by a surge in luteinizing hormone (LH). It involves the release of a mature egg from the ovary into the fallopian tube, where it can be fertilized by sperm.
3. Luteal Phase : Following ovulation, the remaining follicle transforms into the corpus luteum, which produces progesterone. Progesterone maintains the thickened uterine lining, preparing it for potential embryo implantation. If pregnancy does not occur, the corpus luteum degenerates, hormone levels decrease, and menstruation begins again, initiating a new menstrual cycle.

Structural Organisation in Animals

Regulation of Ovarian Function

Hormonal Regulation and Control

1. Hypothalamic-Pituitary-Gonadal Axis : The hypothalamic-pituitary-gonadal (HPG) axis is a hormonal system that oversees ovarian function. It starts with the hypothalamus, which releases gonadotropin-releasing hormone (GnRH). GnRH stimulates the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH act on the ovaries to regulate follicle development, ovulation, and hormone production.
2. Feedback Mechanisms : Feedback mechanisms help maintain hormonal balance within the HPG axis. Negative feedback loops control FSH and LH release by the pituitary gland in response to estrogen and progesterone levels. Elevated estrogen inhibits FSH, while high progesterone levels suppress LH, aiding menstrual cycle regulation.

Factors Influencing Ovarian Function

1. Age : Ovarian function is age-dependent, with ovarian reserve and hormone production declining over time. This decline correlates with reduced follicle quantity and quality, ultimately leading to menopause.
2. Environmental Factors : Environmental elements, like pollutants and toxins, can impact ovarian health. Certain substances, such as endocrine-disrupting chemicals (EDCs), may disrupt hormone production and ovarian function.
3. Lifestyle Factors : Lifestyle choices, including diet, physical activity, and stress levels, can influence ovarian function. Unhealthy eating habits, sedentary behaviour, and chronic stress disrupt hormonal equilibrium and menstrual regularity. Conversely, adopting a balanced diet, engaging in regular exercise, and managing stress can support optimal ovarian function and reproductive well-being.

Common Ovarian Disorders

• Polycystic Ovary Syndrome (PCOS) : PCOS is a hormonal disorder characterized by irregular menstrual periods, excess androgen levels, and polycystic ovaries. Symptoms include irregular periods, acne, excessive hair growth, and infertility.
• Ovarian Cysts : Ovarian cysts are fluid-filled sacs that form on the ovaries. Most cysts are harmless and resolve on their own, but some may cause pain or complications if they rupture or become enlarged.
• Ovarian Cancer : Ovarian cancer is a type of cancer that begins in the ovaries. It often goes undetected until it has spread within the pelvis and abdomen, making it difficult to treat.
• Premature Ovarian Failure : Premature ovarian failure (POF), also known as premature menopause, occurs when the ovaries stop functioning before the age of 40. It leads to infertility and symptoms similar to menopause, such as hot flashes and vaginal dryness.