Female Reproductive System - Ovary: Structure, Function

What Constitutes The Female Reproductive System?

The female reproductive system, unlike the male, is endowed with organs that take up the role of nurturing and creating new life. The organs are the ovaries, fallopian tubes, uterus, cervix, and vagina. All the parts partake in the reproduction of the human from the birth of an ovum to its fertilization, fetal nurturing- and childbirth.

In this system, the ovaries are important in the production of eggs and hormones which contribute to the development process involved in reproduction and regulating menstrual cycles. Their function is critical for fertility and general reproductive health.

Overview of the Ovary

The ovary is a necessary reproductive organ responsible for the production of eggs and secretion of hormones. A study regarding its structure and function is necessary to apprehend its role within the female reproductive system.

Anatomy Of The Ovary

• They lie on either side of the uterus

• Hang off the lateral wall of the pelvis.

• Connected to the uterus by the ovarian ligament.

• Closer to the fallopian tubes that trap the eggs when they are released.

• They lie within the ovarian fossa, a shallow depression on the wall of the pelvis.

The Structure Of Ovary

The structure of the ovary is described below:

Cortex

• It constitutes the outermost layer of the ovary

• Contains ovarian follicles at various stages of development

• Extensive connective tissue and vessels

Medulla

• The central part of the ovary

• Loose connective tissue

• Blood vessels, lymphatic vessels, and nerves

Primordial Follicles

• Smallest and numerous

• Completely immature, primary oocytes

• Contains a single layer of cells known as granulosa cells

Secondary Follicles

• Extensive, with multiple layers of granulosa cells

• The first appearance of a fluid-filled cavity is known as an antrum.

Graafian (Mature) Follicles

• Fully developed and ready for ovulation

• Large antrum surrounded by cumulus oophorus cells.

Function Of The Ovary

The ovary performs two main functions:

• Development of the egg and hormonal functions to facilitate reproduction.

• Regulate the menstrual cycle.

Oogenesis

• Begins in fetal development and ends at menopause

• Growth and maturation of the oocyte takes place within the ovarian follicles

Stages Of Oogenesis

The stages of oogenesis are given below:

Primordial Germ Cells

• Predecessor of the oocyte, produced in early fetal development

Primary Oocytes

• At birth, the result of mitosis and arrest in prophase I

• Contained within primordial follicles

Secondary Oocytes

• What happens after the first meiotic division is complete in the menstrual cycle,

• Is suspended in metaphase II until the time of fertilization.

Mature ovum

• If fertilization occurs, the ovum finishes the second meiotic division and an ovum forms.

• The mature ovum fuses with sperm and results in a zygote to form an embryo.

Hormone Secretion

The hormonal control is explained below-

Estrogen And Production Of Progesterone

• The hormones are secreted by the ovarian follicles and the corpus luteum

• Both the anterior pituitary

• Development of the endometrial lining during the follicular phase.

• Maintenance of secondary sex characteristics.

Progesterone

• Preparation of the endometrium for implantation during the luteal phase.

• Maintenance of pregnancy via supporting the uterine lining.

Ovarian Cycle

• The ovarian cycle is comprised of phases that prepare the body for a potential pregnancy.

• It is intricately regulated, hormonally talking. It is important to understand these phases, and their regulation to appreciate female reproductive physiology.

Phases Of The Ovarian Cycle

The phases of the ovarian cycle are:

Follicular Phase

• Starting from day one of menstrual bleeding, it continues until ovulation, so it roughly extends to 14 days.

• Many follicles within the ovaries begin to grow due to follicle-stimulating Hormones.

• One follicle starts and continues to mature while the rest start degenerating.

• The maturing follicle results in the formation of increased production and release of estrogen.

Hormonal Alterations

• Mounting estrogen levels stimulates an increase in the thickness of the lining of the uterus, endometrium, in anticipation of the nidation of a fertilized egg.

• Provide a diagram explaining follicle development and hormonal changes in the follicular phase.

Ovulation

• Usually one day—approximately Day 14 of the menstrual cycle

• A marked rise in the concentration of Luteinizing Hormone

• The ovum is released, and if fertilized transit into the fallopian tube

Hormonal Changes

• LH surge is the reliable index for Ovulation.

Luteal Phase

• From ovulation to before menstruation starts (for about 14 days)

• The ruptured follicle develops as the corpus luteum. Corpus luteum secretes progesterone, and to some level, estrogen too.

• Progesterone sustains the developed, thickened endometrium, in readiness for implantation.

Hormonal Changes

• If fertilization doesn't occur, corpus luteum degenerates and fats and progesterone levels drop.

• This decline in hormone levels triggers the menstruation of the uterine lining.

Regulation Of The Ovarian Cycle

The ovarian cycle is under the control of hormonal signals from the hypothalamus and pituitary gland.

Hypothalamus

• It releases Gonadotropin-Releasing Hormone GnRH) in a pulsatile manner.

• GnRH acts on the anterior pituitary gland, causing the release of FSH and LH.

Pituitary Gland

• FSH stimulates the growth of follicles in the ovary.

• LH surge causes ovulation and development of the corpus luteum.

Feedback Loops

• Positive Feedback: Increasing levels of estrogen in the follicular phase cause GnRH release resulting in an LH surge and ovulation

• Negative Feedback: In the luteal phase, a high level of progesterone and estrogen have negative inhibition on GnRH, FSH and LH to ensure no other follicles mature.

Common Ovarian Disorders

Several types of disorders may harm the tissues of the ovary reduce ovarian health and impair the overall reproductive functions.

Polycystic Ovary Syndrome (PCOS)

The details of the disorder are given below:

Symptoms

• Irregular menstrual cycles

• Acne and oily skin

• Weight gain and inability to lose weight

• Infertility

Causes

• Hormonal imbalance (hyper androgens)

• Insulin resistance

• Genetic

Treatment

• Diet and exercise

• Medicines to treat irregular menses (oral contraceptive pills)

Ovarian Cysts

The details of the disorder are given below:

Types

• Functional cysts (follicular cysts, corpus luteum cysts)

• Pathological cysts (dermoid cysts, endometriomas, cystadenomas)

Symptoms

• Pelvic pain

• Bloating and abdominal discomfort

• Pain during intercourse

• Irregular menstrual cycles

Management

• Watchful waiting (monitoring small, asymptomatic cysts)

• Medications (hormonal contraceptives to prevent future cysts)

• Surgery (laparoscopy or laparotomy for large or persistent cysts)

Ovarian Cancer

The details of the disorder are given below:

Risk Factors

• Age (most common in women over 50)

• Family history of ovarian or breast cancer

• Genetic mutations (BRCA1 and BRCA2)

• Hormone replacement therapy

• Endometriosis

Symptoms

• Abdominal bloating or swelling

• Pelvic pain

• Difficulty eating or feeling full quickly

• Urinary symptoms (urgency or frequency)

Diagnosis

• Pelvic examination

• Imaging tests (ultrasound, CT scan)

• Blood tests (CA-125)

• Biopsy and histopathological analysis

Recommended Video On 'Female Reproductive System - Ovary'