What Are Gonads?
Gonads are the primary reproductive organs - male gonads are the testes, and female gonads are the ovaries. They produce sperm and ova or eggs, respectively. They are also capable of hormone secretion.
What Are the Male Gonads?
Male gonads are the testes or testicles that are oval shaped present within a sac or a loose bag of skin called the scrotum. They are about the size of bigger olives. The testicle is held in place with the help of a spermatic cord which supplies the testicles with blood. The scrotum is located behind the penis. The testes secrete testosterone, an androgen, or a male sex hormone. Usually, two testicles, one on either side of the scrotum, are present. A coiled mass of tubes is present within the testicles, called seminiferous tubules. These tubules help to produce sperm cells through the process called spermatogenesis.
How Are Male Gonads Formed?
Male gonads develop relatively early in the developmental stages. Initially, gonads appear as gonadal ridges and are differentiated later on to form either male or female sex organs. The SRY gene on the Y chromosome is responsible for differentiation into male sex organs. This gene encodes the testis determining factor, a DNA (deoxyribonucleic acid)-binding protein that initiates determination into male sex organs. Gonadal development occurs parallelly with the development of the urinary organs, as they are a part of the developmental process of reproductive and urinary organs.
What Are the Functions of the Testicles?
The testicles are responsible for producing and storing sperm. They produce testosterone, store sperm, and are the body's primary source of male hormones (testosterone).
Testosterone is necessary for the following functions:
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Male reproductive growth, including the growth and development of reproductive organs.
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Muscular and skeletal growth.
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Male sex drive.
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Enlargement of the larynx (voice box) with the associated changes in voice commonly experienced by boys when they attain puberty.
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Facial and body hair growth.
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Wide shoulders.
How Do Male Gonads Produce Gametes?
Spermatogenesis is the term used for sperm cell production by the testes. This is a continuous process within the testes that occurs by meiosis or division of cells. For example, the male germ cell (also called a spermatocyte) goes through the cell division process called meiosis that divides it into two, with each half receiving half of the chromosomes present in the parent cell. These sperm cells with half the chromosomes may fuse with a similar female sex cell with half the chromosomes from its parent cell - and together, they form a cell called a zygote with a complete set of chromosomes that is a mix of the male and female. The zygote grows into an embryo, a fetus, and eventually a newborn baby.
What Are the Functions of the Sex Hormones?
Sex hormones are essentially steroid hormones with the ability to influence and alter gene expression in their target cells. Hormones produced by the gonads rely on the anterior pituitary gland in the brain for regulation. The anterior pituitary gland secretes hormones that regulate the gonadal hormones. Of these, the specific hormones that control sex hormone production by stimulating the gonads to produce these sex hormones are called gonadotropins.
Gonadotropins secreted by the pituitary gland include
- Luteinizing Hormone (LH)- Stimulates testosterone production by stimulating the testes.
- Follicle-Stimulating Hormone (FSH)- Responsible for the production of sperm.
Hormones of the Male Gonad-
The hormones responsible for male reproductive growth and development are the androgens. They are also produced to a lesser extent in women but are primarily made in men. The testes primarily secrete testosterone as the primary male androgen. The other male gonadal hormones are androstenedione and inhibin.
- Testosterone- Responsible for male sex organ development, male sex characteristics, increased skeletal and muscular growth, body and facial hair growth, voice changes, and penile growth.
- Androstenedione- This hormone forms the precursor hormone to testosterone and estrogen hormones.
- Inhibin- Regulates sperm cells and is also responsible for sperm cell development.
What Are Gonadal Disorders?
Gonadal disorders are caused by dysfunction in hormone levels. They indicate that the testes or the gonads are dysfunctional, implying that sperm and testosterone production will also be affected. The consequences of gonadal disorders can be quite troubling and problematic:
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Hypogonadism- Hypogonadism is a condition where testosterone and/or sperm produced is insufficient for normal functioning.
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Sexual dysfunction.
How Are Gonadal Disorders Diagnosed?
Testosterone levels are usually highest in the morning and tend to drop by at least 13 percent over the day. For this reason, a blood test done in the morning would provide a near-perfect estimate of the actual drop in testosterone levels due to disease rather than as a result of natural physiological function.
How Are Gonadal Disorders Treated?
Hormone replacement therapy is the go-to treatment option for gonadal disorders. These may come in gels, patches, injections, pellets, and pumps. The patches and gels can be directly applied to the skin and are absorbed into the skin.
How Are Sex Hormones Regulated?
Sex hormone regulation depends on several factors, including other hormones called tropic hormones, sex organs, and glands. The release of sex hormones by the testes is regulated by hormones called gonadotropins. The anterior pituitary gland is responsible for the secretion of the tropic hormones and the gonadotropins (specifically LH and FSH), while the secretion of gonadotropins is regulated by a tropic hormone called the gonadotropin-releasing hormone (GnRH). The hypothalamus produces the GnRH, the part of the brain that controls hormone production. It causes stimulation of the pituitary gland and causes the release of LH and FSH. The LH and FSH stimulate male gonads to produce and secrete testosterone, estrogen, and progesterone. These hormones circulate in the blood and, in turn, inhibit GnRH, LH, and FSH. This can cause a reduction in the production and secretion of sex hormones. Together, this combination of mechanisms creates a balance in regulating sex hormones.
Conclusion:
The male gonad is a crucial structure that equips the male reproductive system with everything required to perform its functions correctly. From hormone production to sexual characteristic formation and regulation, male gonads are essential for reproduction. Therefore, understanding the male gonad, its development, functions, and disorders is necessary for sex education.
