Human Physiology/The male reproductive system

Human Physiology/The female reproductive system


In easy phrases, replica is the method by which organisms create descendants. This miracle is a attribute that each one dwelling issues have in widespread and units them other than nonliving issues. However although the reproductive system is crucial to protecting a species alive, it isn’t important to protecting a person alive.

In human replica, two sorts of intercourse cells or gametes are concerned. Sperm, the male gamete, and a secondary oocyte (together with first polar physique and corona radiata), the male gamete should meet within the feminine reproductive system to create a brand new particular person. For copy to happen, each the feminine and male reproductive techniques are important. It’s a widespread misnomer to check with a lady’s gametic cell as an egg or ovum, however that is unattainable. A secondary oocyte should be fertilized by the male gamete earlier than it turns into an “ovum” or “egg”.

Whereas each the feminine and male reproductive techniques are concerned with producing, nourishing and transporting both the oocyte or sperm, they’re completely different in form and construction. The male has reproductive organs, or genitals, which can be each inside and out of doors the pelvis, whereas the feminine has reproductive organs fully inside the pelvis.

The male reproductive system consists of the testes and a collection of ducts and glands. Sperm are produced within the testes and are transported via the reproductive ducts. These ducts embrace the epididymis, vas deferens, ejaculatory duct and urethra. The reproductive glands produce secretions that turn into a part of semen, the fluid that’s ejaculated from the urethra. These glands embrace the seminal vesicles, prostate gland, and bulbourethral glands.


The human male reproductive system


The testes (singular, testis) are situated in the scrotum (a sac of pores and skin between the higher thighs). Within the male fetus, the testes develop close to the kidneys, then descend into the scrotum simply earlier than start. Every testis is about 1 half of inches lengthy by 1 inch large. Testosterone is produced within the testes which stimulates the manufacturing of sperm in addition to give secondary intercourse traits starting at puberty.


The 2 testicles are every held in a fleshy sac known as the scrotum. The most important perform of the scrotal sac is to maintain the testes cooler than thirty-seven levels Celsius (ninety-eight level six levels Fahrenheit). The exterior look of the scrotum varies at completely different occasions in the identical particular person relying upon temperature and the next contraction or rest of two muscle tissue. These two muscle tissue contract involuntarily when it’s chilly to maneuver the testes nearer to the warmth of the physique within the pelvic area. This causes the scrotum to seem tightly wrinkled. Quite the opposite, they calm down in heat temperatures inflicting the testes to decrease and the scrotum to turn into flaccid. The temperature of the testes is maintained at about thirty-five levels Celsius (ninety-five levels Fahrenheit), which is under regular physique temperature. Temperature must be decrease than regular to ensure that spermatogenesis (sperm manufacturing) to happen.

The scrotum is in a relaxed state.

Penile shrinkage on account of low temperatures. The scrotum is in a tense state to manage testicular temperatures.

The 2 muscle tissue that regulate the temperature of the testes are the dartos and cremaster muscle tissue:

The dartos muscle is a layer of easy muscle fibers within the subcutaneous tissue of the scrotum (surrounding the scrotum). This muscle is answerable for wrinkling up the scrotum, in circumstances of chilly climate, with a purpose to keep the right temperature for spermatogenesis.

The cremaster muscle is a skinny strand of skeletal muscle related to the testes and spermatic wire. This muscle is a continuation of the interior indirect muscle of the stomach wall, from which it’s derived.
Seminiferous Tubules

Every testis accommodates over 100 yards of tightly packed seminiferous tubules. Round 90% of the burden of every testes consists of seminiferous tubules.
The seminiferous tubules are the purposeful items of the testis, the place spermatogenesis takes place. As soon as the sperm are produced, they moved from the seminiferous tubules into the rete testis for additional maturation.

Interstitial Cells (Cells of Leydig)

In between the seminiferous tubules inside the testes, are instititial cells, or, Cells of Leydig. They’re answerable for secreting the male intercourse hormones (i.e., testosterone).

Sertoli Cells

A Sertoli cell (a sort of sustentacular cell) is a ‘nurse’ cell of the testes which is a part of a seminiferous tubule.

It’s activated by follicle-stimulating hormone, and has FSH-receptor on its membranes.

Its predominant perform is to nurture the growing sperm cells via the levels of spermatogenesis. Due to this, it has additionally been known as the “mom cell.” It gives each secretory and structural help.

Different features
In the course of the Maturation section of spermiogenesis, the Sertoli cells devour the unneeded parts of the spermatazoa.

Efferent ductules

The sperm are transported out of the testis and into the epididymis via a collection of efferent ductules.

Blood Provide

The testes obtain blood via the testicular arteries (gonadal artery). Venous blood is drained by the testicular veins. The appropriate testicular vein drains immediately into the inferior vena cava. The left testicular vein drains into the left renal vein.


The seminiferous tubules be part of collectively to turn into the epididymis. The epididymis is a tube that’s about 2 inches that’s coiled on the posterior floor of every testis. Throughout the epididymis the sperm incomplete their maturation (full maturation happen in feminine genital tract) and their flagella turn into cell. That is additionally a web site to retailer sperm, nourishing them till the subsequent ejaculation. Easy muscle within the wall of the epididymis propels the sperm into the ductus deferens.

Vasa efferentia from the rete testis open into the epididymis which is a extremely coiled tubule. The epididymis has three parts- 1)head or caput epididymis- it’s the proximal a part of the epididymis. It carries the sperms from the testis.
2)physique or corpus epididymis- it the extremely convoluted center a part of the epididymis
3)tail or cauda epididymis- it’s the final half that takes half in carrying the sperms to the vas deferens. The cauda epididymis continues to type much less convoluted vas deferens.

Ductus Deferens[edit]

The ductus (vas) deferens, additionally known as sperm duct, or, spermatic deferens, extends from the epididymis within the scrotum by itself aspect into the stomach cavity via the inguinal canal. The inguinal canal is a gap within the stomach wall for the spermatic wire (a connective tissue sheath that accommodates the ductus deferens, testicular blood vessels, and nerves. The sleek muscle layer of the ductus deferens contracts in waves of peristalsis throughout ejaculation.

Seminal Vesicles[edit]

The pair of seminal vesicles are posterior to the urinary bladder. They secrete fructose to supply an power supply for sperm and alkalinity to reinforce sperm mobility. The duct of every seminal vesicle joins the ductus deferens on that aspect to type the ejaculatory duct.

Ejaculatory Ducts[edit]

There are two ejaculatory ducts. Every receives sperm from the ductus deferens and the secretions of the seminal vesicle by itself aspect. Each ejaculatory ducts empty into the only urethra.

Prostate Gland[edit]

The prostate gland is a muscular gland that surrounds the primary inch of the urethra because it emerges from the bladder. The sleek muscle of the prostate gland contracts throughout ejaculation to contribute to the expulsion of semen from the urethra.

Bulbourethral Glands[edit]

Pre ejaculate produced by the bulbourethral glands

The bulbourethral glands additionally known as Cowper’s glands are situated under the prostate gland and empty into the urethra. The alkalinity of seminal fluid helps neutralize the acidic vaginal pH and permits sperm mobility in what may in any other case be an unfavorable atmosphere.


The penis is an exterior genital organ. The distal finish of the penis is known as the glans penis and is roofed with a fold of pores and skin known as the prepuce or foreskin. Throughout the penis are lots of erectile tissue. Every consists of a framework of easy muscle and connective tissue that accommodates blood sinuses, that are giant, irregular vascular channels.


The urethra, which is the final a part of the urinary tract, traverses the corpus spongiosum and its opening, often known as the meatus, lies on the tip of the glans penis. It’s each a passage for urine and for the ejaculation of semen.

Overview of Male Reproductive System Construction and Operate[edit]

Bulbourethral glands (2) Pea sized organs posterior to the prostate on both aspect of the urethra. Secretion of gelatinous seminal fluid known as pre-ejaculate. This fluid helps to lubricate the urethra for spermatozoa to go via, and to assist flush out any residual urine or overseas matter. (< 1% of semen)
Cells of Leydig (Interstitial cells of Leydig) Adjoining to the seminiferous tubules within the testicle. Answerable for manufacturing of testosterone. Intently associated to nerves.
Cremaster muscle Covers the testes. Raises and lowers scrotum to assist regulate temperature and promote spermatogenesis. Voluntary and involuntary contraction.
Dartos muscle Layer of easy muscular fiber outdoors the exterior spermatic fascia however under the pores and skin Contraction by wrinkling to lower floor space obtainable for warmth loss to testicles, or growth to extend floor space obtainable to advertise warmth loss; additionally helps elevate and decrease scrotum to assist regulate temperature
Efferent ductules A part of the testes and join the rete testis with the epididymis Ducts for sperm to get to epididymis
Ejaculatory ducts (2) Begins on the vas deferens, passes via the prostate, and empties into the urethra on the Colliculus seminalis. Causes reflex for ejaculation. Throughout ejaculation, semen passes via the ducts and exits the physique through the penis.
Epididymis Tightly coiled duct mendacity simply outdoors every testis connecting efferent ducts to vas deferens. Storage and maturation of sperm.
Penis Three columns of erectile tissue: two corpora cavernosa and one corpus spongiosum. Urethra passes via penis. Male reproductive organ and likewise male organ of urination.
Prostate gland Surrounds the urethra slightly below the urinary bladder and may be felt throughout a rectal examination. Shops and secretes a transparent, barely alkaline fluid constituting as much as one-third of the quantity of semen. Elevate vaginal pH.(25-30% of semen)
Scrotum Pouch of pores and skin and muscle that holds testicles. Regulates temperature at barely under physique temperature.
Semen Normally white however may be yellow, grey or pink (blood stained). After ejaculation, semen first goes via a clotting course of after which turns into extra liquid. Elements are sperm, and “seminal plasma”. Seminal plasma is produced by contributions from the seminal vesicle, prostate, and bulbourethral glands.
Seminal vesicles (2) Convoluted construction connected to vas deferens close to the bottom of the urinary bladder. About 65-75% of the seminal fluid in people originates from the seminal vesicles. Comprise proteins, enzymes, fructose, mucus, vitamin C, flavins, phosphorylcholine and prostaglandins. Excessive fructose concentrations present nutrient power for the spermatozoa as they journey via the feminine reproductive system.
Seminiferous tubules (2) Lengthy coiled construction contained within the chambers of the testis; joins with vas deferens. Meiosis takes place right here, creation of gametes (sperm).
Sertoli cells Junctions of the Sertoli cells type the blood-testis barrier, a construction that partitions the interstitial blood compartment of the testis from the stomach compartment of the seminiferous tubules. Cells answerable for nurturing and improvement of sperm cells , gives each secretory and structural help; activated by FSH. Additionally known as “mom cells” or “nurse cells”.
Testes Inside scrotum, outdoors of physique. Gonads that produce sperm and male intercourse hormones.Manufacturing of testosterone by cells of Leydig within the testicles.
Testicular arteries (Gonadal arteries) Department of the stomach aorta. It’s a paired artery. Every passes obliquely downward and laterally behind the peritoneum. Provides blood to the testes.
Urethra Connects bladder to outdoors physique, about Eight inches lengthy. Tubular construction that receives urine from bladder and carries it to outdoors of the physique. Additionally passage for sperm.
Vas deferens Muscular tubes connecting the left and proper epididymis to the ejaculatory ducts to maneuver sperm. Every tube is about 30 cm lengthy. Throughout ejaculation the sleek muscle within the vas deferens wall contracts, propelling sperm ahead. Sperm are transferred from the vas deferens into the urethra, amassing fluids from accent intercourse glands on route

Composition of human semen[edit]

The parts of semen come from two sources: sperm, and “seminal plasma”. Seminal plasma, in flip, is produced by contributions from the seminal vesicle, prostate, and bulbourethral glands.

Seminal plasma of people accommodates a posh vary of natural and inorganic constituents.

The seminal plasma gives a nutritive and protecting medium for the spermatozoa throughout their journey via the feminine reproductive tract. The traditional atmosphere of the vagina is a hostile one for sperm cells, as it is extremely acidic (from the native microflora producing lactic acid), viscous, and patrolled by immune cells. The parts within the seminal plasma try and compensate for this hostile atmosphere. Fundamental amines comparable to putrescine, spermine, spermidine and cadaverine are answerable for the scent and taste of semen. These alkaline bases counteract the acidic atmosphere of the vaginal canal, and defend DNA contained in the sperm from acidic denaturation.

The parts and contributions of semen are as follows:

testes 2-5% Roughly 200- to 500-million spermatozoa (additionally known as sperm or spermatozoans), produced within the testes, are launched per ejaculation
seminal vesicle 65-75% amino acids, citrate, enzymes, flavins, fructose (the principle power supply of sperm cells, which rely fully on sugars from the seminal plasma for power), phosphorylcholine, prostaglandins (concerned in suppressing an immune response by the feminine in opposition to the overseas semen), proteins, vitamin C
prostate 25-30% acid phosphatase, citric acid, fibrinolysin, prostate particular antigen, proteolytic enzymes, zinc (serves to assist to stabilize the DNA-containing chromatin within the sperm cells. A zinc deficiency might lead to lowered fertility due to elevated sperm fragility. Zinc deficiency may adversely have an effect on spermatogenesis.)
bulbourethral glands < 1% galactose, mucus (serve to extend the mobility of sperm cells within the vagina and cervix by making a much less viscous channel for the sperm cells to swim via, and stopping their diffusion out of the semen. Contributes to the cohesive jelly-like texture of semen.), pre-ejaculate, sialic acid

A 1992 World Well being Group report described regular human semen as having a quantity of two ml or larger, pH of seven.2 to eight.0, sperm focus of 20×106 spermatozoa/ml or extra, sperm depend of 40×106 spermatozoa per ejaculate or extra and motility of 50% or extra with ahead development (classes a and b) of 25% or extra with fast development (class a) inside 60 minutes of ejaculation.[1]


Male reproductive hormone chart.gif

Hormone Regulation[edit]

Hormones which management replica in males are:

Gonadotropin-Releasing Hormone (GnRH):

  • The hypothalamus secretes this hormone into the pituitary gland within the mind.
  • There are two gonadotropic hormones, FSH and LH.

Luteinizing Hormone (LH):

  • The pituitary gland secretes this hormone after receiving a GnRH sign from the hypothalamus.
  • LH stimulates Leydig cells, within the testes, telling them to supply testosterone.

Follicle-Stimulating Hormone (FSH):

  • The pituitary gland additionally secretes this hormone.
  • Testosterone helps FSH run via the bloodstream to make Sertoli cells, situated within the seminiferous tubules of the testes, to make immature sperm to mature sperm.


  • Also referred to as “the male hormone” and “androgen”.
  • Testosterone is important for the manufacturing of sperm.

The constituent cavernous cylinders of the penis.


Transverse part of the penis.

The erection of the penis is its enlarged and agency state. It relies on a posh interplay of psychological, neural, vascular and endocrine components. The time period can be utilized to the method that results in this state.

A penile erection happens when two tubular constructions that run the size of the penis, the corpora cavernosa, turn into engorged with venous blood. This can be a results of parasympathetic nerve induced vasodilation. This may increasingly outcome from any of assorted physiological stimuli. The corpus spongiosum is a single tubular construction situated slightly below the corpora cavernosa, which accommodates the urethra, via which urine and semen go throughout urination and ejaculation, respectively. This may increasingly additionally turn into barely engorged with blood, however much less so than the corpora cavernosa.

Penile erection often outcomes from sexual stimulation and/or arousal, however may happen by such causes as a full urinary bladder or spontaneously in the course of the course of a day or at night time, usually throughout erotic or moist goals. An erection ends in swelling and enlargement of the penis. Erection allows sexual activity and different sexual actions (sexual features), although it isn’t important for all sexual actions.


Emission is the time period used when sperm strikes into the urethra. Ejaculation is the time period used when sperm is compelled out of the urethra and the penis. These are each stimulated by sympathetic nerves.

Sperm Manufacturing[edit]

A spermatozoon or spermatozoan (pl. spermatozoa), from the traditional Greek σπέρμα (seed) and ζῷον (dwelling being) and extra generally often known as a sperm cell, is the haploid cell that’s the male gamete.

Spermatagonia divides a number of occasions in the course of the means of sperm improvement. Your entire means of sperm formation and maturation takes about 9-10 weeks. The separate divisions that happen and what occurs in every are as follows:

  • First division: The primary division is finished by mitosis, and ensures a relentless provide of spermatocytes, every with the diploid variety of chromosomes.
  • Second division: Spermatocytes then endure a collection of two cell divisions throughout meiosis to turn into secondary spermatocytes.
  • Third division: Secondary Spermatocytes lastly turn into spermatids. Spermatids, that are haploid cells, mature slowly to turn into the male gametes, or sperm.

The sperm is the principle reproductive cell in males. The sperms differ in that every carry a set of chromosomes dividing every into both a male, or feminine sperm. The females differ in that they carry a X gene, whereas the male sperm carry a Y gene. The feminine sperm additionally differ phenotypically in that they’ve a bigger head compared to the male sperms. This contributes to the male sperm being lighter, and subsequently quicker and stronger swimmers than their feminine counterparts (though statistically there may be nonetheless a 50% likelihood of an both XY or XX embryo forming.

Spermatozoan stream strains are straight and parallel. The tail flagellates, which we now know propels the sperm cell (at about 1-Three mm/minute in people) by rotating like a propeller, in a round movement, not aspect to aspect like a whip. The cell is characterised by a minimal of cytoplasm. Throughout fertilization, the sperm’s mitochondria will get destroyed by the egg cell, and this implies solely the mom is ready to present the infant’s mitochondria and mitochondrial DNA, which has an necessary utility in tracing maternal ancestry. Nevertheless it has been lately found that mitochondrial DNA may be recombinant.

Spermatozoa are produced within the seminiferous tubules of the testes in a course of known as spermatogenesis. Spherical cells known as spermatogonia divide and differentiate ultimately to turn into spermatozoa. Throughout copulation the vagina is inseminated, the spermatozoa transfer via chemotaxis (see glossary) to the ovum inside a Fallopian tube or the uterus.

Sperm Pathway[edit]

Spermatogenesis takes place inside a male’s testes, particularly within the partitions of the seminiferous tubules. The epididymis is a tortuously coiled construction topping the testis, it receives immature sperm from the testis and shops it for a number of days. When ejaculation happens, sperm is forcefully expelled from the tail of the epididymis into the ductus deferens. Sperm travels via the ductus deferens and up the spermatic wire into the pelvic cavity, over the ureter to the prostate behind the bladder. Right here, the vas deferens joins with the seminal vesicle to type the ejaculatory duct, which passes via the prostate and empties into the urethra. Upon the sperm’s exit from the testes, into the vas deferens, muscular actions take over. When ejaculation happens, rhythmic muscle actions of peristalsis propel the sperm ahead. This continues all through the rest of the sperm’s journey via the male reproductive system.

Sperm cells turn into much more lively after they start to work together with the fertilizing layer of an egg cell. They swim quicker and their tail actions turn into extra forceful and erratic. This conduct is known as “hyper activation.”

A current discovery hyperlinks hyper activation to a sudden inflow of calcium ions into the tails. The whip-like tail (flagellum) of the sperm is studded with ion channels fashioned by proteins known as CatSper. These channels are selective, permitting solely calcium ion to go. The opening of CatSper channels is answerable for the inflow of calcium. The sudden rise in calcium ranges causes the flagellum to type deeper bends, propelling the sperm extra forcefully via the viscous atmosphere.

Acrosome response on a Sea Urchin cell

The sperm use their tails to push themselves into the epididymis, the place they full their improvement. It takes sperm about Four to six weeks to journey via the epididymis. The sperm then transfer to the vas deferens, or sperm duct. The seminal vesicles and prostate gland produce a whitish fluid known as seminal fluid, which mixes with sperm to type semen when a male is sexually stimulated.

The penis, which often hangs limp, turns into arduous when a male is sexually excited. Tissues within the penis fill with blood and it turns into stiff and erect (an erection). The rigidity of the erect penis makes it simpler to insert into the feminine’s vagina throughout sexual activity, and the prolonged size permits it to achieve deeper into the feminine’s oviduct, the passage from the ovaries to the surface of the physique (permitting a shorter journey distance for the spermatozoa).

When the erect penis is stimulated to orgasm, muscle tissue across the reproductive organs contract and pressure the semen via the duct system and urethra. Semen is pushed out of the male’s physique via his urethra – ejaculation. The pace of the semen is about 70 mph when ejaculation comes and it will possibly include 100 to 600 million sperm cells. When the male ejaculates throughout intercourse, semen is deposited into the fornix on the base of the feminine’s vagina, close to the cervix. From the fornix, the sperm make their approach up via the cervix and transfer via the uterus with assist from uterine contractions.

Sperm hyperactivity is important for breaking via two bodily limitations that defend the egg from fertilization.
The primary barrier to sperm is made up of so-called cumulus cells embedded in a gel-like substance made primarily of hyaluronic acid. The cumulus cells develop within the ovary with the egg and help it because it grows.

The second barrier coating the oocyte is a thick shell fashioned by glycoproteins known as the zona pellucida. One of many proteins that make up the zona pellucida binds to a associate molecule on the sperm. This lock-and-key kind mechanism is species-specific and prevents the sperm and egg of various species from fusing. There’s some proof that this binding is what triggers the acrosome to launch the enzymes that enable the sperm to fuse with the egg.

When a sperm cell reaches the egg the acrosome releases its enzymes. These enzymes weaken the shell, permitting the sperm cell to penetrate it and attain the plasma membrane of the egg. A part of the sperm’s cell membrane then fuses with the egg cell’s membrane, and the sperm cell sinks into the egg (at which level the sperm tail falls off).

Upon penetration, the egg cell membrane undergoes a change and turns into impenetrable, stopping additional fertilization.

The binding of the sperm to an ovum is known as a zygote. A zygote is a single cell, with an entire set of chromosomes, that usually develops into an embryo.


Along with producing sperm, the male reproductive system additionally produces intercourse hormones, which assist a boy develop right into a sexually mature man throughout puberty. When a child boy is born, he has all of the components of his reproductive system in place, but it surely is not till puberty that his reproductive organs mature and turn into totally purposeful. As an new child FSH and LH ranges are excessive and after just a few weeks ranges drop to extraordinarily low. When puberty begins, often between the ages of 10 and 14, the pituitary gland – which is situated within the mind – secretes hormones that stimulate the testicles to supply testosterone. The manufacturing of testosterone brings about many bodily modifications. Though the timing of those modifications is completely different for every particular person male, the levels of puberty usually comply with a set sequence.

  • First stage: the scrotum and testes develop bigger, the apocrine glands develop (see clarification of apocrine glands in glossary).
  • Second stage: the penis turns into longer, and the seminal vesicles and prostate gland develop. Hair begins to develop within the pubic area. Reproductive capability has often developed by this stage.
  • Third stage: hair begins to seem on the face and underarms. Throughout this time, a male’s voice additionally deepens. Fertility continues to extend.

Testicular measurement, perform, and fertility[edit]

In boys, testicular enlargement is the primary bodily manifestation of puberty (and is termed gonadarche). Testes in prepubertal boys change little in measurement from about 1 yr of age to the onset of puberty, averaging about 2–Three cc in quantity and about 1.5-2 cm in size. Testicular measurement continues to extend all through puberty, reaching maximal grownup measurement about 6 years later. Whereas 18-20 cc is reportedly a mean grownup measurement, there may be large variation within the regular inhabitants.

The testes have two major features: to supply hormones and to supply sperm. The Leydig cells produce testosterone (as described under), which in flip produces many of the modifications of male puberty. Nevertheless, many of the growing bulk of testicular tissue is spermatogenic tissue (primarily Sertoli and interstitial cells). The event of sperm manufacturing and fertility in males isn’t as properly researched. Sperm may be detected within the morning urine of most boys after the primary yr of pubertal modifications (and infrequently earlier).


A boy’s penis grows little from the fourth yr of life till puberty. Common prepubertal penile size is Four cm. The prepubertal genitalia are described as stage 1. Inside months after development of the testes begins, rising ranges of testosterone promote development of the penis and scrotum. This earliest discernible starting of pubertal development of the genitalia is known as stage 2. The penis continues to develop till about 18 years of age, reaching a mean grownup measurement of about 10-16 cm.

Though erections and orgasm can happen in prepubertal boys, they turn into way more widespread throughout puberty, accompanied by improvement of libido (sexual need).
Ejaculation turns into potential early in puberty; previous to this boys might expertise dry orgasms. Emission of seminal fluid might happen on account of masturbation or spontaneously throughout sleep (generally termed a moist dream, and extra clinically known as a nocturnal emission). The power to ejaculate is a reasonably early occasion in puberty in comparison with the opposite traits, and may happen even earlier than reproductive capability itself. In parallel to the irregularity of the primary few durations of a lady, for the primary one or two years after a boy’s first ejaculation, his seminal fluid might include few lively sperm.

If the foreskin of a boy doesn’t turn into retractable throughout childhood, it usually begins to retract throughout puberty. This happens on account of the elevated manufacturing of testosterone and different hormones within the physique.

Distribution of androgenic hair on feminine and male physique

Genital Erection[edit]

The penis accommodates two chambers known as the corpora cavernosa, which run the size of the organ. A spongy tissue, filled with muscle, veins, arteries, and so forth. fills these chambers. The corpora cavernosa are surrounded by a membrane, known as the tunica albuginea.

Erection begins with sensory or psychological stimulation, or each. Impulses from the mind and native nerves trigger the muscle tissue of the corpora cavernosa to calm down, permitting blood to circulation in and fill the areas. The blood creates stress within the corpora cavernosa, making the penis broaden. The tunica albuginea helps lure the blood within the corpora cavernosa, thereby sustaining erection. When muscle tissue within the penis contract to cease the influx of blood and open outflow channels, erection is reversed.

Pubic hair in boys[edit]

Pubic hair usually seems on a boy shortly after the genitalia start to develop. As in ladies, the primary look of pubic hair is termed pubarche and the pubic hairs are often first seen on the dorsal (stomach) base of the penis. The primary few hairs are described as stage 2. Stage Three is often reached inside one other 6 to 12 months, when the hairs are too quite a few to depend. By stage 4, the pubic hairs densely fill the “pubic triangle.” Stage 5 refers to unfold of pubic hair to the interior thighs and upward in the direction of the umbilicus as a part of the growing stomach hair.

Sexual Homology[edit]

The human male reproductive system

Cross-sectional diagram of the feminine reproductive organs.

Briefly, this can be a identified checklist of intercourse organs that evolve from the identical tissue in a human life.

Detached Male Feminine
Gonad Testis Ovary
Mullerian duct Appendix testis Fallopian tubes
Mullerian duct Prostatic utricle Uterus, proximal vagina
Wolffian duct Rete testis Rete ovarii
Mesonephric tubules Efferent ducts Epoophoron
Wolffian duct Epididymis Gartner’s duct
Wolffian duct Vas deferens
Wolffian duct Seminal vesicle
Wolffian duct Prostate Skene’s glands
Urogenital sinus Bladder, urethra Bladder, urethra, distal vagina
Urogenital sinus Bulbourethral gland Bartholin’s gland
Genital swelling Scrotum Labia majora
Urogenital folds Distal urethra Labia minora
Genital tubercle Penis Clitoris
Prepuce Foreskin Clitoral hood
Bulb of penis Vestibular bulbs
Glans penis Clitoral glans
Crus of penis Clitoral crura

For many males, testosterone secretion continues all through life, as does sperm manufacturing, although each diminish with advancing age. In all probability the most typical reproductive downside for older males is prostatic hypertrophy, enlargement of the prostate gland. This causes the urethra to compress and urination turns into troublesome. Residual urine within the bladder will increase the prospect of urinary tract infections. Prostate hypertrophy is often benign, however most cancers of the prostate is among the extra widespread cancers in aged males. A TURP is often used to appropriate this downside if the signs don’t enhance in response to dwelling remedy and medicine.

Erectile dysfunction (ED) is one other widespread downside seen in growing older males. In older males, ED often has a bodily trigger, comparable to illness, harm, or unwanted effects of medication. Any dysfunction that impairs blood circulation within the penis or causes harm to the nerves has the potential to trigger ED. Though it isn’t an inevitable a part of growing older, incidences will increase with age: About 5 % of 40-year-old males and between 15 and 25 % of 65-year-old males expertise ED. As discouraging as Erectile dysfunction could also be, it’s treatable at any age, and consciousness of this reality has been rising. Extra males have been searching for assist and returning to regular sexual exercise due to improved, profitable remedies for ED.

Issues that may go flawed with the male reproductive system[edit]

Boys might typically expertise reproductive system issues. Under are some examples of problems that have an effect on the male reproductive system (Problems of the Scrotum, Testicles, or Epididymis). Situations affecting the scrotal contents might contain the testicles, epididymis, or the scrotum itself.

  • Testicular trauma. Even a light harm to the testicles may cause extreme ache, bruising, or swelling. Most testicular accidents happen when the testicles are struck, hit, kicked, or crushed, often throughout sports activities or on account of different trauma. Testicular torsion, when 1 of the testicles twists round, chopping off the blood provide, can be an issue that some teen males expertise – though it is not widespread. Surgical procedure is required to untwist the wire and save the testicle.
  • Varicocele. This can be a varicose vein (an abnormally swollen vein) within the community of veins that run from the testicles. Varicoceles generally develop whereas a boy goes via puberty. A varicocele is often not dangerous, though in some folks it could harm the testicle or lower sperm manufacturing, so it helps so that you can take your baby to see his physician if he’s involved about modifications in his testicles.
  • Testicular most cancers. This is among the commonest cancers in males youthful than 40. It happens when cells within the testicle divide abnormally and type a tumor. Testicular most cancers can unfold to different components of the physique, but when it is detected early, the remedy fee is superb. Teen boys ought to be inspired to be taught to carry out testicular self-examinations.
  • Epididymitis is irritation of the epididymis, the coiled tubes that join the testes with the vas deferens. It’s often attributable to an an infection, such because the sexually transmitted illness chlamydia, and ends in ache and swelling subsequent to 1 of the testicles.
  • Hydrocele. A hydrocele happens when fluid collects within the membranes surrounding the testes. Hydroceles might trigger swelling of the testicle however are usually painless. In some instances, surgical procedure could also be wanted to appropriate the situation.
  • Inguinal hernia. When a portion of the intestines pushes via an irregular opening or weakening of the stomach wall and into the groin or scrotum, it is called an inguinal hernia. The hernia might appear like a bulge or swelling within the groin space. It may be corrected with surgical procedure.

Problems of Penis[edit]

Problems of the Penis
Problems affecting the penis embrace the next:

  • Irritation of the penis. Signs of penile irritation embrace redness, itching, swelling, and ache. Balanitis happens when the glans (the pinnacle of the penis) turns into infected. Posthitis is foreskin irritation, which is often on account of a yeast or bacterial an infection.
  • Hypospadias. This can be a dysfunction through which the urethra opens on the underside of the penis, not on the tip.
  • Phimosis. This can be a tightness of the foreskin of the penis and is widespread in newborns and younger kids. It often resolves itself with out remedy. If it interferes with urination, circumcision (elimination of the foreskin) could also be advisable.
  • Paraphimosis. This may increasingly develop when a boy’s uncircumcised penis is retracted however would not return to the unretracted place. In consequence, blood circulation to the penis could also be impaired, and your baby might expertise ache and swelling. A health care provider might attempt to use lubricant to make a small incision so the foreskin may be pulled ahead. If that does not work, circumcision could also be advisable.
  • Ambiguous genitalia. This happens when a toddler is born with genitals that are not clearly male or feminine. In most boys born with this dysfunction, the penis could also be very small or nonexistent, however testicular tissue is current. In a small variety of instances, the kid might have each testicular and ovarian tissue.
  • Micro penis. This can be a dysfunction through which the penis, though usually fashioned, is properly under the common measurement, as decided by normal measurements.
  • Sexually transmitted illnesses. Sexually transmitted illnesses (STDs) that may have an effect on boys embrace human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), human papillomavirus (HPV, or genital warts), syphilis, chlamydia, gonorrhea, genital herpes, and hepatitis B. They’re unfold from one particular person to a different primarily via sexual activity.
  • Erectile dysfunction. E.D. is the lack to get or hold an erection agency sufficient for sexual activity. This could additionally known as impotence. The phrase “impotence” may additionally be used to explain different issues that may intervene with sexual activity and replica, comparable to issues with ejaculation or orgasm and lack of sexual need. Utilizing the time period erectile dysfunction clarifies that these different issues aren’t concerned.

Contraceptive for Males[edit]

Within the process the vas deferens of every testes is reduce and tied off to forestall the passage of sperm. Sperm continues to be produced and saved in crypt websites inflicting irritation. Due to this inflammatory response the immune system acts on them destroying them after which having antisperm antibodies. This causes a decrease chance if the vasectomy is reversed to turning into fertile once more.

Condoms: A tool, often product of latex, or extra lately polyurethane, that’s used throughout sexual activity. It’s placed on a person’s penis and bodily blocks ejaculated semen from coming into the physique of a sexual associate. Condoms are used to forestall being pregnant, transmission of sexually transmitted illnesses (STDs – comparable to gonorrhea, syphilis, and HIV), or each.

Evaluation Questions[edit]

Solutions for these questions may be discovered right here

1. That is wanted to make immature sperm mature


2. These turn into engorged with blood in an erection

A) corpora cavernosa
B) fibrous envelope
C) septum pectiniforme
D) integument
E) dorsal veins

3. The distinction between female and male sperm

A) feminine sperm have a bigger head
B) male sperm are lighter
C) feminine sperm are quicker
D) male sperm are weaker
E) A and B
F) C and D

4. Your entire means of sperm formation takes about

A) 5-6 weeks
B) 7-Eight weeks
C) 3-Four weeks
D) 9-10 weeks

5. Hyper Activation happens when

A) the sperm are launched into the urethra
B) the sperm are ejaculated into the vaginal canal
C) the sperm start to work together with the fertilizing layer of an egg cell
D) the sperm attain the cervix

6. It takes sperm ___________ weeks to journey via the epididymis

A) 6-8
B) 1-3
C) 2-4
D) 4-6

7. Whereas singing within the choir, Ben immediately notices his voice is continually cracking. That is attributable to

A) androgens
D) Ben’s lack of ability to sing

8. In sexual homology, the glans penis within the male is the same as _____________ within the feminine

A) clitoral hood
B) clitoris
C) clitoral glans
D) clitoral crura

9. In sexual homology, the ___________ within the male is the same as the fallopian tubes within the feminine

A) testis
B) appendix testis
C) vas deferens
D) seminal vesicle
E) efferent ducts

10. Joe has a bulge within the groin space that appears to worsen when he lifts issues. This probably is

A) epididymitis
B) testicular most cancers
C) varicocele
D) hydrocele
E) inguinal hernia


Androgen: The generic time period for any synthetic or natural compound, often a steroid hormone, that stimulates or controls the event and upkeep of masculine traits in vertebrates by binding to androgen receptors. This contains the exercise of the accent male intercourse organs and improvement of male secondary intercourse traits. They’re additionally the precursor of all estrogens, the feminine intercourse hormones. The first and most well-known androgen is testosterone.

Apocrine Glands: Apocrine sweat glands develop in the course of the early to mid puberty ages roughly across the age of 15 and launch greater than regular quantities of sweat for about a month and subsequently regulate and launch regular quantities of sweat after a sure time frame. They’re situated wherever there may be physique hair.
These glands produce sweat that accommodates fatty supplies. Primarily current within the armpits and across the genital space, their exercise is the principle explanation for sweat odor, as a result of micro organism that break down the natural compounds within the sweat.

Bulbourethral Glands: male accent intercourse glands that secrete mucus for lubrication

Chemotaxis: Chemotaxis is a sort of taxis, through which bodily cells, micro organism, and different single-cell or multicellular organisms direct their actions in line with sure chemical substances of their atmosphere. That is necessary for micro organism to seek out meals (for instance, glucose) by swimming in the direction of the very best focus of meals molecules, or to flee from poisons (for instance, phenol). In multicellular organisms, chemotaxis is crucial to improvement in addition to regular perform. As well as, it has been acknowledged that mechanisms that enable chemotaxis in animals may be subverted throughout most cancers metastasis.

Corpora Cavernosa: one in all a pair of a sponge-like areas of erectile tissue which include many of the blood within the male penis throughout erection

Ductus Deferens: epididymal ducts from every testis converge to type a big, thick walled, muscular duct

Ejaculatory Ducts: two ducts, obtain sperm from the ductus deferens and secretions from the seminal vesicle; the ducts then empty into the urethra

Epididymis: comma formed and loosely connected to the rear floor of every testis

Erectile Tissue: easy muscle and connective tissue contained in the penis that include blood sinuses; giant, irregular vascular channels

Erection: the penis at its enlarged and agency state; happens when the corpora cavernosa turn into engorged with venous blood

Flagellum: the whip-like tail of a sperm, propels the sperm in the direction of the egg in hopes of attaining fertilization

Follicle-Stimulating Hormone (FSH): hormone that stimulates manufacturing of sertoli cells, to make immature sperm to mature sperm

Glans Penis: distal finish of the penis, lined with the foreskin

Gonadotropin-Releasing Hormone (GnRH): hormone secreted by the hypothalamus into the pituitary gland; two varieties, FSH and LH

Libido: In its widespread utilization, it means sexual need; nevertheless, extra technical definitions, comparable to these discovered within the work of Carl Jung, are extra common, referring to libido because the free inventive—or psychic—power a person has to place towards private improvement, or individuation.

Luteinizing Hormone (LH): hormone that stimulates Leydig cells within the testes to supply testosterone

Oviduct: the passage in females from the ovaries to the surface of the physique.

Penis: exterior genital organ of the male

Prostate Gland: male accent intercourse gland that secretes an alkaline fluid, which neutralizes acidic vaginal secretions

Puberty: the interval of maturation and arousal of the dormant and nonfunctional reproductive system; often happens in males between the ages of 10 and 15

Scrotum: pores and skin lined sac that homes the male testicles; retains the testicles away type the physique in order that they’ll keep just a few levels cooler than the physique, for higher sperm manufacturing

Seminal Vesicle: male accent intercourse glands that offer fructose to ejaculated sperm and secrete prostaglandins

Seminiferous Tubules: extremely coiled tubules inside the testes that produce spermatozoa

Sertoli Cell: A Sertoli cell (a sort of sustentacular cell) is a ‘nurse’ cell of the testes which is a part of a seminiferous tubule.

It’s activated by follicle-stimulating hormone, and has FSH-receptor on its membranes.

Its predominant perform is to nurture the growing sperm cells via the levels of spermatogenesis. Due to this, it has additionally been known as the “mom cell.” It gives each secretory and structural help.

Sexual Homology: intercourse organs that evolve from the identical tissues in each male and females

Sperm: predominant reproductive cell in males

Spermatogenesis: sperm manufacturing

Testes: situated within the scrotum, produces testosterone which stimulates manufacturing of sperm

Testosterone: male intercourse hormone secreted by the leydig cells of the testes, very important for the manufacturing of sperm

TURP: transurethral resection of the prostate. Throughout TURP, an instrument is inserted up the urethra to take away the part of the prostate that’s blocking urine circulation. That is mostly attributable to benign prostatic hyperplasia (BPH). A TURP often requires hospitalization and is finished utilizing a common or spinal anesthetic. It’s now the most typical surgical procedure used to take away a part of an enlarged prostate.

Urethra: the final a part of the urinary tract; in males, it’s the passage for each urine and sperm

Varicocele: varicose vein of the testicles, typically a explanation for male infertility

Vasectomy: commonest sterilization process in males; small phase of every ductus deferens is surgically eliminated after it passes from the testis


Each female and male reproductive techniques could appear considerably remoted from different physique techniques in that their goal is to create new life and never simply to keep up current life. There are nevertheless important relationships between the reproductive system and different physique techniques. All techniques relate in a method or one other to assist our our bodies keep homeostasis.


  1. Male Infertility from A to Z: A Concise Encyclopedia. Google books

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