Male reproductive system is an organ system that has been modified to make male reproductive cells called sperm and to transport them to the female reproductive system for reproduction. It is also one of the organs that produce important hormones, such as testosterone, which is responsible for the development and function of male reproductive organs and for male secondary sexual characteristics.
Reproduction requires the coordinated activity of multiple organs and glands in man and many other mammals. The male reproductive system consists of both the outside and the inside reproductive organs. Major organs include the testes, the epididymis, the vas (ductus) deferens, the ejaculatory ducts, the urethra, the penis, the scrotum, the seminal vesicles, the prostate gland, and the bulbourethral glands.
In Zoology appreciation of male reproductive system is important because reproduction is one of the important phenomena of living organisms. The reproductive system plays a role in the species' survival and provides an example of the interdependence of organs, hormones, cells and physiology.
Main Parts of the Male Reproductive System
Male reproductive system consists of 4 parts namely Primary reproductive organs, Reproductive duct, Accessory glands and external genital organs.
Testicles are the main reproductive organs as they produce sperm and male sex hormones. Sperm is moved from the testes to the urethra via the reproductive duct. Accessory glands secrete fluids into sperm to make it into semen. The penis and urethra are involved in the delivery of semen.
1. Testes
The testes, also called testicles, are the main reproductive organs of males. Two testes (testicles) are normally located outside the main body cavity in the scrotum.
Each testis is oval-shaped and is surrounded by protective layers. The interior of the testis is subdivided into numerous small compartments or lobules. In each lobule are one or more highly coiled seminiferous tubules.
The seminiferous tubules are very significant because it is in these tubules that the production of sperm cells, called spermatogenesis, occurs. These tubules have walls lined by developing sperm cells and supporting Sertoli cells.
Leydig cells, or interstitial cells are located between the seminiferous tubules. These cells respond to these hormones and make testosterone.
Therefore, the functions of the testes are two-fold:
- Production of sperm
- Production of testosterone
- The testes are thus both repro and endocrine glands.
2. Scrotum
The testes are enclosed in a pouch of skin and muscle called the scrotum. It is located outside the abdominal cavity.
The location of the testes within the scrotum is essential as the production of sperm is dependent on a slightly cooler temperature than the normal body temperature. The scrotum is used to retain this temperature by contracting the muscles.
As the outside temperature cools, the scrotal muscles tighten and bring the testicles towards the body. As temperature increases the muscles relax and the testes can move further away from the body.
This is crucial for the normal production of sperm.
3. Epididymis
The epididymis is a long coiled tube on the back of each testis. Sperm that are newly produced move from the seminiferous tubules to the epididymis.
Sperm that leave the testes are immature and do not move as well. As they pass through the epididymis they are subject to important maturation processes.
The epididymis can be divided into three broad areas:
- Head
- Body
- Tail
Sperm is carried towards the head from the testis and the tail is joined to the vas.
The epididymis can thus be said to be valuable for the storage and maturation of sperm.
4. Vas Deferens
The vas or ductus deferens is a muscular tube which carries the sperm from the epididymis to the ejaculatory duct.
When a man ejaculates, the wall of the vas muscle contracts which moves sperm forward.
Vas moves upward from the scrotum and is then in the pelvis. It will ultimately fuse with the duct of the seminal vesicle to form the ejaculatory duct.
So, the role of the vas is primarily to transport mature sperm.
5. Ejaculatory Ducts
The ejaculatory ducts are formed when the vas deferens joins the ducts of the seminal vesicles.
Typically two ejaculatory ducts are found, one on each side of the reproductive system. They go through the prostate and connect with the urethra.
Their primary role is to channel the sperm and glandular secretions into the urethra during ejaculation.
6. Urethra
The passage of the penis through which urine leaves the body from the urinary bladder is the urethra.
The urethra is a double organ in males. It is the channel through which urine passes, and a passage for the semen. But, urine and semen do not flow through the same urethra at the same time.
Ejaculation is a time when the reproductive pathway is closed, in part by the action of muscles.
The urethra is thus the last outlet for semen to pass from the male reproductive system.
Accessory Reproductive Glands
There are accessory glands in the male reproductive system. These glands create fluids, which combine with sperm to create a fluid known as semen.
The large accessory glands are the:
- Seminal vesicles
- Prostate gland
- Bulbourethral glands
7. Seminal Vesicles
The seminal vesicles are two glands that are behind the urinary bladder.
They contribute a large amount of the fluid part of semen. They secrete substances which provide energy and support to the sperm.
One of the key components is fructose, a sugar that is the energy source for sperm cells.
Semenoggerin secreted in the seminal vesicles also plays a role in the volume and chemical composition of semen.
As the semen passes through the reproductive ducts, the secretions of the seminal vesicles mix with the sperm and other glandular fluids.
atOptions = { 'key' : '9ce9e0d0dab3e7f39667081acfffdc77', 'format' : 'iframe', 'height' : 90, 'width' : 728, 'params' : {} };
8. Prostate Gland
The prostate gland is a gland located below the urinary bladder and surrounding part of the urethra.
It secretes fluid that is incorporated into the semen. The prostatic secretions contain substances which are necessary to the proper functioning and survival of sperm.
Clinically the prostate has importance as well. For men, the prostate can enlarge as they grow older and this can make it difficult to pass urine since the urethra (the tube through which urine is expelled) runs through the prostate.
Thus, the prostate also plays a significant role in the health and reproductive function.
9. Bulbourethral Glands
Cowper's glands, also known as the bulbourethral glands, are small paired glands that are found below the prostate.
They secrete a clear fluid which lubricates the urethra and makes the passage of the penis ready for ejaculation.
They are small glands whose secretions are part of the function of the male reproductive system.
External Reproductive Organs
The external reproductive organs are the penis and scrotum.
10. Penis
The penis is the male organ of sexual intercourse and the discharge of semen into the female reproductive tract.
It has some special erectile tissues which can fill with blood and result in an erection.
The penis is made up, in general:
- Root
- Shaft
- Glans
The end of the penis is enlarged and is called the glans penis. It is covered by a piece of skin in many males that is known as the foreskin or prepuce.
When reproduction is sexual, the penis may be used to allow for the transfer of semen into the female reproductive system.
The structure of a sperm cell.
The male reproductive cell or male gamete is the sperm. It is very specialized for the purpose of reaching and fertilizing an egg.
The three major regions of a mature sperm cell are:
Head
The male genetic material is stored in the head in the form of a nucleus. A cap-like structure known as the acrosome is at the head or anterior end.
Spermatozoa have an acrosome which is filled with enzymes that are used to fuse with and penetrate the protective layers of the egg cell during fertilization.
Middle Piece
Numerous mitochondria are present in the middle piece. These mitochondria generate the energy that is needed to move the sperm.
Tail
The flagellum or tail is used for propulsion. Its vibrating action enables the sperm to travel through the reproductive tract.
The shape of the sperm is thus very similar to its function, the head containing genetic material, the middle piece containing energy and the tail containing motility.
Spermatogenesis
The production of sperm cells in the seminiferous tubules of the testes is called spermatogenesis.
It starts with specialised germ cells and stages of cell division and maturation.
The main phases are:
- Spermatogonia
- Primary spermatocytes
- Secondary spermatocytes
- Spermatids
- Spermatozoa
Spermatogonia divide and develop into primary spermatocytes. These cells divide specially called meiosis which halves the chromosome number.
The resulting cells are then transformed into spermatids. A mature sperm is formed from spermatids by a process called spermiogenesis.
Sertoli cells nourish and establish proper conditions for the development of sperm (spermatogenesis).
Discuss the hormonal regulation of the male reproductive system.Talk about hormones that regulate the male reproductive system.
The male reproductive system is under the control of a complex interplay between the brain, pituitary and testes. Also known as the hypothalamic-pituitary-gonadal axis.
Hormone Gonadotropin-releasing hormone, or GnRH is released by the hypothalamus. GnRH stimulates the pituitary gland to release two important hormones:
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
Role of FSH
- The primary action of FSH is on the Sertoli cells in the testes. It helps in the production of sperm.
Role of LH
- LH sydig cells in the testes to make Testosterone.
Role of Testosterone
- Testosterone is the most important male sex hormone. It has significant functions in:
- In males, the testicles start to develop.Male reproductive organs begin to develop.
Sperm production
- Maturing of male secondary sex characteristics
- Maintenance of sexual function
- Growth and maintenance of muscle and bones
- Control of reproductive activities.
- These hormones are regulated by feedback mechanisms to help regulate reproductive balance.
- atOptions = { 'key' : '9ce9e0d0dab3e7f39667081acfffdc77', 'format' : 'iframe', 'height' : 90, 'width' : 728, 'params' : {} };
Formation of Semen
Semen is a substance that comes out of the male reproductive system when he is ejaculating. It includes secretions from the accessory reproductive glands and sperm cells.
The testicles make sperm that pass through the epididymis and the vas. Fluid from the seminal vesicles, the prostate gland and bulbourethral glands are added along the way.
The resulting mixture will nourish the sperm, act as a transport medium, and create a proper environment for the sperm.
Sperm and semen need to be differentiated. Sperm is a single reproductive cell while semen is a combination of this reproductive cell and glandular fluids.
Ejaculation
It secretes fluid that is incorporated into the semen. The prostatic secretions contain substances which are necessary to the proper functioning and survival of sperm.
Clinically the prostate has importance as well. For men, the prostate can enlarge as they grow older and this can make it difficult to pass urine since the urethra (the tube through which urine is expelled) runs through the prostate.
Thus, the prostate also p
9. Bulbourethral Glands
Cowper's glands, also known as the bulbourethral glands, are small paired glands that are found below the prostate.They secrete a clear fluid which lubricates the urethra and makes the passage of the penis ready for ejaculation.
They are small glands whose secretions are part of the function of the male reproductive system.
External Reproductive Organs
The external reproductive organs are the penis and scrotum.
10. Penis
The penis is the male organ of sexual intercourse and the discharge of semen into the female reproductive tract.It has some special erectile tissues which can fill with blood and result in an erection.
The penis is made up, in general:
- Root
- Shaft
- Glans
When reproduction is sexual, the penis may be used to allow for the transfer of semen into the female reproductive system.
The structure of a sperm cell.
The male reproductive cell or male gamete is the sperm. It is very specialized for the purpose of reaching and fertilizing an egg.
The three major regions of a mature sperm cell are:
Head
The male genetic material is stored in the head in the form of a nucleus. A cap-like structure known as the acrosome is at the head or anterior end.Spermatozoa have an acrosome which is filled with enzymes that are used to fuse with and penetrate the protective layers of the egg cell during fertilization.
Middle Piece
Numerous mitochondria are present in the middle piece. These mitochondria generate the energy that is needed to move the sperm.Tail
The flagellum or tail is used for propulsion. Its vibrating action enables the sperm to travel through the reproductive tract.The shape of the sperm is thus very similar to its function, the head containing genetic material, the middle piece containing energy and the tail containing motility.
Spermatogenesis
The production of sperm cells in the seminiferous tubules of the testes is called spermatogenesis.It starts with specialised germ cells and stages of cell division and maturation.
The main phases are:
- Spermatogonia
- Primary spermatocytes
- Secondary spermatocytes
- Spermatids
- Spermatozoa
The resulting cells are then transformed into spermatids. A mature sperm is formed from spermatids by a process called spermiogenesis.
Sertoli cells nourish and establish proper conditions for the development of sperm (spermatogenesis).
Discuss the hormonal regulation of the male reproductive system.Talk about hormones that regulate the male reproductive system.
The male reproductive system is under the control of a complex interplay between the brain, pituitary and testes. Also known as the hypothalamic-pituitary-gonadal axis.
Hormone Gonadotropin-releasing hormone, or GnRH is released by the hypothalamus. GnRH stimulates the pituitary gland to release two important hormones:
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
Role of FSH
The primary action of FSH is on the Sertoli cells in the testes. It helps in the production of sperm.Role of LH
LH stimulates Leydig cells in the testes to make Testosterone.Role of Testosterone
Testosterone is the most important male sex hormone. It has significant functions in:In males, the testicles start to develop.Male reproductive organs begin to develop.
Sperm production
- Maturing of male secondary sex characteristics
- Maintenance of sexual function
- Growth and maintenance of muscle and bones
- Control of reproductive activities.
- These hormones are regulated by feedback mechanisms to help regulate reproductive balance.
Formation of Semen
Semen is a substance that comes out of the male reproductive system when he is ejaculating. It includes secretions from the accessory reproductive glands and sperm cells.The testicles make sperm that pass through the epididymis and the vas. Fluid from the seminal vesicles, the prostate gland and bulbourethral glands are added along the way.
The resulting mixture will nourish the sperm, act as a transport medium, and create a proper environment for the sperm.
Sperm and semen need to be differentiated. Sperm is a single reproductive cell while semen is a combination of this reproductive cell and glandular fluids.
.jpg)
.jpg)
.png)
0 Comments