Gonads - Definition, Meaning, Function, Topics, Diagnosis, Care

What Are Gonads?

The gonads are part of reproductive organs which become the primary sex organs of both males and females. They function in the production of gamete and sex hormones. The male gonads are testes while in females, they are ovaries. These organs have a big responsibility in conducting sexual reproduction and also secondary sexual characteristics or traits.

Structure and Function of Gonads

The structure and function of gonads are described:

Testes (Male Gonads)

Location: External to the male body, within the scrotum

Function:

• Production of sperm through spermatogenesis

• Secretion of testosterone

Ovaries (Female Gonads)

Location: Within the pelvic cavity, on opposite sides of the uterus

Function:

• Production of ova through oogenesis

• Production of estrogen and progesterone

Gonadal Hormones and Their Functions

The gonadal hormones and their functions are:

Testosterone

• Maintains the secondary sex characteristics of males like facial hair, deeper voice, increasing muscle mass and bone density

• Regulates libido and male reproductive health.

Estrogen

• Development of female secondary sex characteristics including growth of breasts and wider pelvis.

• Maintains menstrual cycle

• Maintains reproductive system health

Progesterone

• Prepares the uterus for pregnancy

• Maintains early pregnancy stages.

• Progesterone, together with estrogen, regulates the menstrual cycle

Reproductive Functions of Gonads

The reproductive functions of gonads are:

Spermatogenesis

The process of sperm production by the testes by which spermatogonia mature to become spermatozoon.

Oogenesis

Oogenesis is the process of egg formation in the ovaries where ovarian follicles develop to finally release an egg via ovulation.

Significance of Gonads in Reproductive Health

The significance of gonads in reproductive health is:

Fertility

Fertility in males and females depends on the gonadal function. It has been established that hormonal imbalance or structural defect may lead to infertility.

Control of Menstrual Cycle

The menstrual cycle is regulated by the cyclical production of estrogen and progesterone. In addition to that, these two hormones will physically prepare the body for a pregnancy that may occur.

Puberty and Sexual Maturation

Gonadal hormones are responsible for physical changes during puberty and sexual maturation.

Detailed Anatomy Of The Testes

Below is described the anatomy of the testes

Seminiferous Tubules

These are highly coiled structures wherein spermatogenesis occurs.

Leydig Cells

Interstitium between seminiferous tubules, responsible for the production of testosterone.

Epididymis

This is a long, coiled tube that lies next to the testis wherein the sperm mature and are stored.

Blood Supply and Innervation of Testes

Blood supply and Innervation of testes is discussed below:

Arterial supply: The testes receive most of their arterial supply through the testicular arteries.

Venous drainage: The venous drainage is through the pampiniform plexus and this has an important role in thermoregulation.

Nervous supply: Autonomic nerves that help regulate blood flow and temperature.

Anatomy of the Ovaries

Below is described the anatomy of ovaries

• Follicles: A sac that contains the immature ova that develop and ripen during the menstrual cycle.

• Corpus Luteum: A temporary endocrine structure involved in the production of progesterone following ovulation.

• Stroma: Connective tissue that provides support to ovarian follicles and blood vessels.

Blood Supply and Innervation of Ovaries

Blood supply and Innervation of ovaries is discussed below:

• Arterial supply: By the ovarian arteries, which arise as branches from the abdominal aorta.

• Venous drainage: By the ovarian veins.

• Nervous supply: Autonomic nerves that act on the ovaries.

Lifestyle and Gonadal Health

Lifestyle matters when it is about gonadal health

Diet and Nutrition

Antioxidant intake: protects sperm and egg from damage

Essential nutrients: Zn, Se and Folic acid are essential for reproduction.

Exercise

Moderate exercise: Promotes Hormonal Balance and Reproductive function

Excessive Exercise: Causes hormonal imbalance and reproductive dysfunction

Gonads NEET MCQs (With Answers & Explanations)

Important questions asked in NEET from this topic are:

• Types of gonadal hormones

• Hormones and their functions

Practice Questions for NEET

Q1. Which ONE of the following statements is TRUE concerning the human ovary?

1. Estrogen is secreted by Graafian follicles and progesterone by the corpus luteum.

2. Estrogen is secreted by the corpus luteum and progesterone by Graafian follicles.

3. Both estrogen and progesterone are secreted by the corpus luteum.

4. Both estrogen and progesterone are secreted by Graafian follicles.

Correct answer: 1) Estrogen is secreted by Graafian follicles and progesterone by the corpus luteum.

Explanation:

Graafian follicle – a fluid-filled structure in the mammalian ovary within which an ovum develops before ovulation. A corpus luteum refers to the composition of the cells that produce the hormone progesterone. The corpus luteum forms into the ovary after the discharge of an ovum. However, it degenerates after some days as its roles depend on fertilization.

Hence, the correct answer is option 1) Estrogen is secreted by Graafian follicles and progesterone by corpus luteum.

Q2. _____ Regulates sex characters, mammary gland development, development of growing ovarian follicles etc

1. Estrogen

2. Relaxin

3. Prolactin

4. Progesterone

Correct answer: 1) Estrogen

Explanation:

Estrogens produce wide-ranging actions such as stimulation of growth and activities of female secondary sex organs, development of growing ovarian follicles, the appearance of female secondary sex characters (e.g., the high pitch of voice, etc.), and mammary gland development. Estrogens also regulate female sexual behaviour

Hence, the correct answer is option 1) Estrogen.

Q3. Name a peptide hormone which acts mainly on hepatocytes, and adipocytes and enhances cellular glucose uptake and utilization.

1. Insulin

2. Glucagon

3. Secretin

4. Gastrin

Correct answer: 1) Insulin

Explanation:

Insulin - Insulin is a peptide hormone, which plays a major role in the regulation of glucose homeostasis. Insulin acts mainly on hepatocytes and adipocytes (cells of adipose tissue) and enhances cellular glucose uptake and utilization

Hence, the correct answer is option 1) Insulin.

Also Read:

• MCQs on Gonads

• Pituitary Gland

• Adrenal Gland

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