It consists of different sex organs that play a vital role in the process of human reproduction. The male reproductive system is present outside the body in the pelvic region. It includes a pair of testes along with accessory ducts, accessory glands and the external genitalia. Testes are situated outside the abdominal cavity within the scrotum. Major organs of reproduction in males includes the penis, and the testicles which produces semen and sperm(i.e. male sex gametes) during copulation.
Scrotum
It is connected to the abdominal or pelvic cavity via inguinal canals. This canal helps in the passage of spermatic cord into the testis. Spermatic artery, vein and nerve all bounded together with connective tissue to form spermatic cord. The vital function of scrotum is to maintain optimum temperature for sperm production. The temperature of testes is maintained by scrotum at around 34°C which is a temperature 2-2.5°C lower than the normal internal body temperature (37°C), since high temperatures do not favour sperm development.
Testis and Seminiferous Tubules
Each testis is oval shaped, with a length of 4-5 cm and width of 2-3 cm. The three layers surrounding the testis includes:
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Tunica Vaginalis
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Tunica Albuginea
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Tunica Vasculosa
Each testis includes about 250 compartments referred to as testicular lobules. One to three highly coiled seminiferous tubules are present in lobules, which produce sperms. Two types of cells lining each seminiferous tubule includes:
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Male germ cells (spermatogonia): it undergoes meiotic divisions leading to sperm production
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Sertoli cells: these provide nutrition to the germ cells
Regions present outside the seminiferous tubules are known as interstitial spaces, containing small blood vessels and interstitial cells or Leydig cells. Testicular hormones called androgens are secreted by Leydig cells. There are two functions performed by testis:
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Production of sperms
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Secretion of male sex hormones
Male Accessory Ducts
The accessory ducts present in males are divided into rete testis, vasa efferentia, epididymis and vas deferens. The seminiferous tubules open inside the vasa efferentia via rete testis. Epididymis located along the posterior surface of each testis, vasa efferentia leaves the testis and opens into epididymis. Epididymis is followed via vas deferens which further ascends to the abdomen and hangs over the urinary bladder. The epididymis receives ducts from the seminal vesicle and opens into the urethra as the ejaculatory duct. The epididymis differentiated into:
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Caput Epididymis
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Corpus Epididymis
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Cauda Epididymis
The ejaculatory duct helps in storage and transport of sperms from testis to the outside via urethra. Urethra extends from the urinary bladder up to the penis to its external opening known as the urethral meatus.
Urethra
These are tube-like structures connecting the urinary bladder to the urethral meatus. In male the urethra extends upto the penis. Its function includes:
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This region includes the urinary tract that helps in the passage of urine from the bladder where semen is ejaculated
Penis (external genitalia)
It is known as the copulatory organ of males and serves both in reproduction and urination. Penis includes three cylindrical masses of erectile tissue
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Two dorsal corpora cavernosa
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One ventral corpus spongiosum
These two tissues are further covered by fibrous tissue. A structure known as penile urethra is present in corpus spongiosum . It is an inflated end of penis to form glans penis. A loose fold of skin known as the prepuce or foreskin covers the glans penis.
Male Accessory Glands
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Seminal Vesicles: these are a pair of sac-like structures, located in the pelvis near the base of the bladder. The ducts from the seminal vesicles combine with vasa deferentia to form an ejaculatory duct. The secretions of seminal vesicles are alkaline in nature and form about 60-70 percent volume of the semen. Its pH is generally 7.4. It helps in neutralizing the acidity of males urethra together with the vaginal tract, thereby increasing the life span of sperms. Secretions from seminal vesicles includes fructose (it provides energy to sperms), prostaglandins (stimulates uterine contraction and allows the sperm to move towards the female’s oviduct), and lastly, clotting proteins (it facilitates coagulation of semen after ejaculation)
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Prostate Glands: these are large, chestnut shaped glands surrounding the urethra. Its secretions are slightly alkaline milky fluid, forming about 20-30 percent of the volume of semen. It includes citric acid (that acts as nutrient for sperm) , enzymes (acid phosphates, amylase, etc.), and prostaglandins (helps in activation of sperms to allow them to swim). Secretions from the prostate gland nourishes and activates the spermatozoa to swim
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Bulbourethral Gland: these are also known as Cowper’s Gland. These are paired pea-sized glands located at either side of membranous urethra. The ducts of these glands open into the urethra. Secretions from these glands are alkaline fluid, which helps in neutralising the acidity of urine in the urethra. This also releases mucus at the ends of the penis and lining of urethra which helps in their lubrication
Semen
They are a collection of secretions from seminal vesicles, prostate gland, and Cowper’s glands and sperms from the testes. During ejaculation, semen is ejected from penis. A single ejaculate includes 200 to 300 million sperms. It has a pH of 7.35 to 7.50. Semen provides a fluid medium for sperm transmission, nourishment of sperms and neutralization of the acidity of urine in the urethra of male to protect sperms.
Conclusion
The whole male reproductive system is dependent on hormones. There are chemicals that stimulate or regulate the activities of cells and organs. The main hormones involved in the functioning of male reproductive system are FSH, LH and testosterone. Testosterone also has a major role in the development of male characteristics such as deep male voice, muscle strength and mass, fat deposition, bone mass and sexual drive.00