Cytogenetics and serogentics of Male reproductive system

Cytogenetics

cytogenetics is a branch of genetics that is concerned with the study of the structure and function of the cell…cytogenetics of male and female reproductive physiology means study of the structure and functions of the cells related to reproductive activity — in male : sertoli cells,leydig cells and sperm(germ cell);in female : follicular cell (primordial follicle to ova — female reproductive cycle) 

The purpose of the organs of the male reproductive system is to perform the following functions:

• To produce, maintain, and transport sperm (the male reproductive cells) and protective fluid (semen)
• To discharge sperm within the female reproductive tract during sex
• To produce and secrete male sex hormones responsible for maintaining the male reproductive system

Unlike the female reproductive system, most of the male reproductive system is located outside of the body. These external structures include the penis, scrotum, and testicles.

• Penis: This is the male organ used in sexual intercourse. It has three parts: the root, which attaches to the wall of the abdomen; the body, or shaft; and the glans, which is the cone-shaped part at the end of the penis. The glans, also called the head of the penis, is covered with a loose layer of skin called foreskin. This skin is sometimes removed in a procedure called circumcision. The opening of the urethra, the tube that transports semen and urine, is at the tip of the penis. The glans of the penis also contains a number of sensitive nerve endings.The body of the penis is cylindrical in shape and consists of three circular shaped chambers. These chambers are made up of special, sponge-like tissue. This tissue contains thousands of large spaces that fill with blood when the man is sexually aroused. As the penis fills with blood, it becomes rigid and erect, which allows for penetration during sexual intercourse. The skin of the penis is loose and elastic to accommodate changes in penis size during an erection.Semen, which contains sperm (reproductive cells), is expelled (ejaculated) through the end of the penis when the man reaches sexual climax (orgasm). When the penis is erect, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm.
• Scrotum: This is the loose pouch-like sac of skin that hangs behind and below the penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. The scrotum acts as a “climate control system” for the testes. For normal sperm development, the testes must be at a temperature slightly cooler than body temperature. Special muscles in the wall of the scrotum allow it to contract and relax, moving the testicles closer to the body for warmth or farther away from the body to cool the temperature.

• Testicles (testes): These are oval organs about the size of large olives that lie in the scrotum, secured at either end by a structure called the spermatic cord. Most men have two testes. The testes are responsible for making testosterone, the primary male sex hormone, and for generating sperm. Within the testes are coiled masses of tubes called seminiferous tubules. These tubes are responsible for producing sperm cells.

The internal organs of the male reproductive system, also called accessory organs, include the following:

• Epididymis: The epididymis is a long, coiled tube that rests on the backside of each testicle. It transports and stores sperm cells that are produced in the testes. It also is the job of the epididymis to bring the sperm to maturity, since the sperm that emerge from the testes are immature and incapable of fertilization. During sexual arousal, contractions force the sperm into the vas deferens.
• Vas deferens: The vas deferens is a long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind the bladder. The vas deferens transports mature sperm to the urethra, the tube that carries urine or sperm to outside of the body, in preparation for ejaculation.
• Ejaculatory ducts: These are formed by the fusion of the vas deferens and the seminal vesicles (see below). The ejaculatory ducts empty into the urethra.
• Urethra: The urethra is the tube that carries urine from the bladder to outside of the body. In males, it has the additional function of ejaculating semen when the man reaches orgasm. When the penis is erect during sex, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm.
• Seminal vesicles: The seminal vesicles are sac-like pouches that attach to the vas deferens near the base of the bladder. The seminal vesicles produce a sugar-rich fluid (fructose) that provides sperm with a source of energy to help them move. The fluid of the seminal vesicles makes up most of the volume of a man’s ejaculatory fluid, or ejaculate.
• Prostate gland: The prostate gland is a walnut-sized structure that is located below the urinary bladder in front of the rectum. The prostate gland contributes additional fluid to the ejaculate. Prostate fluids also help to nourish the sperm. The urethra, which carries the ejaculate to be expelled during orgasm, runs through the center of the prostate gland.
• Bulbourethral glands: Also called Cowper’s glands, these are pea-sized structures located on the sides of the urethra just below the prostate gland. These glands produce a clear, slippery fluid that empties directly into the urethra. This fluid serves to lubricate the urethra and to neutralize any acidity that may be present due to residual drops of urine in the urethra.

Testes

The testes, or testicles, are male sex glands that play an important role in the reproductive system. They are the site of sperm production and are also responsible for the production of testosterone. Testosterone is a steroid hormone that is important for a number of bodily functions, not just sex drive and sperm development.

The testes take the form of two, egg-shaped organs located in the scrotum. The scrotum hangs outside the body. The location of the testes outside the abdomen has evolved, at least in part, because the testes need to stay cooler than body temperature to fully function.

Anatomy

Most males are born with two testicles, collectively known as the testes. These soft, egg-shaped organs are located inside the scrotum. They are surrounded by a number of accessory structures including the epididymis and the vas deferens.

The testes are suspended from the abdomen by the spermatic cord. This is a collection of blood vessels, nerves, and ducts that support the health of the testes.¹ A person whose testes remain inside their body is said to have undescended testes.

The testes consist of several lobes, each made up of seminiferous tubules. These tubules are the site in which sperm are produced. As sperm develop and mature they move through the tubules until they are collected in the rete testes and then passed through to the epididymis. The epididymis is where sperm mature before ejaculation.

The testes are enclosed in the tunica albuginea. This fibrous capsule surrounds the testes and also divides it into the lobules that contain the seminiferous tubules. The whole mass is then mostly surrounded by the tunica vaginalis. This covering allows the testes to move smoothly inside the scrotum. In adult males, the testes are 2-3 centimeters (cm) wide by 3-5 cm long.¹ The testes increase in size through adulthood and then decrease in size later in life.

Function

The testes have two primary functions. The first function of the testes is to produce testosterone. Testosterone is a steroid hormone that is responsible for sexual differentiation of the male. It is important for prenatal development. It also regulates the development of primary and secondary sexual characteristics—such as penis size and chest hair.¹ In addition, testosterone contributes to the growth spurt that males experience during puberty, bone and muscle growth, and the formation of blood cells.

The second function of the testes is to produce sperm. Sperm develop inside the network of seminiferous tubules that make up a large portion of the testicles. Unlike females, who have a limited number of germ cells that can turn into eggs across the lifetime, men are able to make millions and millions of sperm every single day. It then takes several months for the sperm to mature enough to be functional upon ejaculation. This maturation starts in the testes but mostly takes place inside the epididymis.

The entire male reproductive system is dependent on hormones, which are chemicals that regulate the activity of many different types of cells or organs. The primary hormones involved in the male reproductive system are follicle-stimulating hormone, luteinizing hormone, and testosterone.

Follicle-stimulating hormone is necessary for sperm production (spermatogenesis), and luteinizing hormone stimulates the production of testosterone, which is also needed to make sperm. Testosterone is responsible for the development of male characteristics, including muscle mass and strength, fat distribution, bone mass, facial hair growth, voice change, and sex drive.

Can a man go through menopause?

Menopause is a term used to describe the end of a woman’s normal menstrual function. In women, this is marked by changes in hormone production. One of the biggest changes for a woman after menopause is that she can no longer have children. The testes, unlike the ovaries, don’t lose the ability to make hormones. If a man is healthy, he may be able to make sperm well into his 80s or longer.

On the other hand, subtle changes in the function of the testes can happen as early as 45 to 50 years of age, and more dramatically after the age of 70. For many men, hormone production may remain normal into old age, while others may have declining hormone production earlier on. This can sometimes be a result of an illness, such as diabetes.

It’s unclear whether decreasing testicular function contributes to symptoms like fatigue, weakness, depression or impotence.