Anatomy that the male Reproductive System

The masculine reproductive system has external (penis, scrotum, epididymus, and testes) and also internal (accessory) organs.

You are watching: The sac containing the male gonad

Key Takeaways

Key PointsThe attributes of the masculine reproductive system include producing and transporting sperm, ejaculating sperm into the female reproductive tract, and also producing and also secreting masculine hormones.Most the the male reproductive system is located outside of the body. These outside structures room the penis, scrotum, epididymis, and also testes.The inner organs of the male reproductive device are referred to as accessory organs. They include the vas deferens, seminal vesicles, prostate gland, and also bulbourethral glands.Key Termssemen: includes spermatozoa, proteolytic and other enzymes, andfructose that promotes spermatozoa survival. It also provides a medium for spermmotility.spermatogenesis: The procedure of sperm manufacturing within the seminiferous tubules in the testes.testosterone: Steroid hormone produced primarily in the masculine testes and responsible because that the development of male an additional sex characteristics.

The offal of the masculine reproductive device are committed for three major functions:

To produce, maintain, transport, and also nourish sperm (the masculine reproductive cells), and protective fluid ( semen ).To discharge sperm in ~ the mrs reproductive tract.To produce and also secrete masculine sex hormones.

External male Sex Organs

Most that the masculine reproductive system is located outside of the man’s body. These exterior structures space the penis, scrotum, epididymis, and testes.


Male Reproductive System: Lateral check out of masculine reproductive mechanism with organs labeled.

The dick is the male organ for sexual intercourse and also urination. Semen and also urine leave the dick through the urethra. The scrotum is a loose, pouch-like sack of skin the hangs behind the penis, containing the testes.

The scrotum has actually a safety function, including the maintain of optimal temperatures because that sperm survival and also function. Because that sperm development, the testes must keep a temperature slightly cooler than typical body temperature. One-of-a-kind muscles in the wall surface of the scrotum contract and also relax in stimulate to move the testes near the body.

The epididymus is situated at the back of the testis and also connects it to the vas deferens. Its duty is to store and also carry sperm. The testis is the place for testosterone production. The coiled arsenal of tubes in ~ the testes space the seminiferous tubules. Within this tubules, spermatogenesis bring away place.

Accessory Sex Organs

The inner organs that the masculine reproductive system are called accessory organs. They incorporate the vas deferens, seminal vesicles, prostate gland, and bulbourethral (Cowper’s) glands.

Vas deferens: Transports mature sperm come the urethra in preparation for ejaculation.Seminal vesicles: Sac-like pouches that connect to the vas deferens near the base of the bladder. The vesicles create molecules such as furustos that offer as power sources for sperm. The seminal vesicle fluid makes up many of the volume the a man’s ejaculate.Prostate gland: A walnut-sized framework located listed below the urinary bladder in front of the rectum. It contributes additional fluid come the ejaculate the serves as nourishment because that sperm.Bulbourethral (Cowper’s) glands: Pea-sized structures located on the political parties of the urethra just listed below the prostate gland. This glands produce a clear, slippery liquid that empties straight into the urethra. Fluid developed by these glands lubricates the urethra and neutralizes acidity associated with residual urine.


The function of the scrotum is to carry out the testes v a chamber of suitable temperature for optimal sperm production.

Learning Objectives

Describe the attributes of the scrotum

Key Takeaways

Key PointsMoving the testes far from the abdomen and increasing the exposed surface area permit a faster dispersion of overabundance heat.If testes were in the abdomen, continuous pressure from abdominal muscles would possibly empty the testes and also epididymis before sperm were sufficiently mature for fertillization.The duty of the scrotum shows up to be to store the temperature of the testes slightly lower than that of the remainder of the body.Key Termsscrotum: The bag the skin and muscle that includes the testes in mammals.testosterone: A steroid hormone the plays a crucial role in masculine reproductive development including the promo of second sexual characteristics.epididymis: A narrow, tightly-coiled tube wherein sperm space stored throughout maturation. The connects the efferent ducts native the behind of every testicle come its vas deferens.

Anatomical Considerations

The scrotum is a dual-chambered suspended sack of skin and also smooth muscle that contains the testes, and is homologous come the labia majora in females. It is an extension of the perineum, and also is located in between the penis and also anus. In humans and some various other mammals, increased testosterone secretion throughout puberty causes the darkening of the skin and breakthrough of pubic hair ~ above the scrotum. The left testis is usually lower than the right, i beg your pardon may role to avoid compression in the event of impact. This asymmetry may likewise allow more effective cooling the the testes.


The function of the scrotum shows up to it is in to store the temperature the the testes slightly reduced than the of the rest of the body. For human beings, the temperature need to be one or two levels Celsius below body temperature (around 35 degrees Celsius or 95 degrees Fahrenheit); higher temperatures might be damaging to sperm count.

The temperature is managed by scrotal movement of the testes far or towards the body relying on the eco-friendly temperatures. Moving the testes away from the abdomen and also increasing the exposed surface area permit a much faster dispersion of overabundance heat. This is done by method of contraction and relaxation the the cremaster muscle and the dartos fascia in the scrotum.

However, temperature regulation might not be the only duty of the scrotum. It has been suggested that if testes were located within the ab cavity, they would be based on the regular changes in abdominal muscle pressure that space exerted by the abdominal muscle muscles, resulting in the an ext rapid emptying of the testes and epididymis of sperm before the spermatozoa were matured sufficiently because that fertilization. Some mammals (elephants and also marine mammals, for example) carry out keep their testes within the abdomen wherein there might be mechanisms to avoid this inadvertent emptying.


The scrotum: image of the external, muscle, and deep tissue views that the scrotum.

Key Takeaways

Key PointsThe testes develop the hormones testosterone and other androgens.Sperm are created within seminiferous tubules.Leydig cell produce and secrete masculine hormones.Sertoli cells assist in the process of spermatogenesis.Key TermsLeydig cells: additionally known together interstitial cells of Leydig, these room found adjacent to the seminiferous tubules in the testicle and produce testosterone in the presence of luteinizing hormone.follicle-stimulating hormone: Stimulates the growth and also recruitment the immature ovarian follicles in females. In males, it is vital for spermatogenesis together it stimulates major spermatocytes to form secondary spermatocytes.sertoli cells: component of the seminiferous tubule that helps in the process of spermatogenesis.Luteinizing hormone: A hormone developed by gonadotropic cells of the anterior pituitary gland. The triggers ovulation and breakthrough of the body luteum in females and stimulates Leydig cell manufacturing of testosterone in males.testes: also referred to as testicles, the masculine gonads in animals.

Testicle: A diagram of the major components of one adult person testis, including the complying with numbered items: 1. Tunica albuginea, 2. Septula testis, 3. Lobulus testis, 4. Mediastinum testis, 5. Tubuli seminiferi contorti, 6. Tubuli seminiferi recti, 7. Rete testis, 8. Ductuli efferentes testis, 9a. Head the epididymis, 9b. Body of epididymis, 9.c Tail of epididymis,10. Vas deferens, 11a. Tunica vaginalis (parietal lamina), 11b. Tunica vaginalis (visceral lamina), and 12. Cavity the tunica vaginalis.

The testis is the male gonad in animals. Like the ovaries to which they space homologous, testes are contents of both the reproductive system and the endocrine system. Thee testes create sperm (spermatogenesis) and androgens, mainly testosterone. Both functions of the testis are affected by gonadotropic hormones developed by the anterior pituitary gland. Luteinizing hormone outcomes in testosterone release. The existence of both testosterone and follicle-stimulating hormone (FSH) is essential to support spermatogenesis.

Almost all healthy male vertebrates have two testes. In mammals, the testes space often contained within an expansion of the abdomen called the scrotum. In mammals with external testes, that is most common for one testicle come hang reduced than the other. While the dimension of the testis varies, that is approximated that 21.9% the men have actually one higher-positioned testis, if 27.3% of men have actually reported equally-positioned testicles.

The difficult membranous shell referred to as the tunica albuginea contains an extremely fine coiled tubes dubbed seminiferous tubules. These space lined v a layer of germ cells that construct into sperm cells (also known as spermatozoa or male gametes) from puberty into old age. The emerging sperm travels through the seminiferous tubules to the rete testis located in the mediastinum testis, come the efferent ducts, and also then to the epididymis whereby newly-created sperm cells mature. The sperm moves into the vas deferens and is eventually expelled through the urethra, via the urethral orifice through muscular contractions.

Leydig cell located between seminiferous tubules produce and also secrete testosterone and other androgens necessary for sexual development and puberty, including secondary sexual features such together facial hair and also sexual behavior. They additionally support libido, spermatogenesis, and also erectile function. In addition, testosterone controls testicular volume. The sertoli cells room the testes’ somatic cells, crucial for testis advance and spermatogenesis.

Inside the human being Testes: diagram illustrates the scrotum through a portion of the covering eliminated to display the testis.

Key Takeaways

Key PointsThe significant structure that the cock is created by columns of corpus cavernosum and also spongiosum tissue.The head that the penis, dubbed the glans, consists of the opened for the urethral duct, the passage because that urine and also seminal fluid.The penis and also clitoris (found in women) are homologous organs.Blood engorgement the penile tissue causes the prick to become erect, facilitating sex-related intercourse.Ejaculation is the release of sperm, which propels the sperm into the quality canal as soon as it occurs throughout intercourse.Key Termsglans: The vascular body which develops the apex the the penis.penis: The male sexual organ for copulation and also urination; the tubular section of the masculine genitalia (excluding the scrotum).intromittent organ: A term because that a male exterior organ that delivers sperm throughout copulation.clitoral glans: highly innervated component of the clitoris the exists at the reminder of the clitoral body as a fibrovascular cap.ejaculation: The forcible ejection of semen native the mammalian urethra, a reflex in an answer to sexual stimulation.

The penis is an intromittent organ of male animals with reproductive and also urinary functions. Unlike numerous other species, the human penis has no baculum, or erectile bone. Instead, the relies entirely on engorgement through blood to accomplish erection. The human penis cannot it is in withdrawn right into the groin, andis larger than that of any kind of other primate, specifically in regards to proportion to human body mass.

Human Penis: This is a chart of a human prick with its components labeled.

Parts of the Penis

The human cock is made up of 3 columns the tissue: two corpora cavernosa the lie alongside each other on the dorsal side and a body spongiosum that lies between the corpora cavernosa ~ above the ventral side. The glans dick is the bulbous finish of the dick formed through the body spongiosum. It support the foreskin (prepuce) the retracts to disclose the glans. The area top top the underside that the penis, whereby the foreskin is attached, is referred to as the frenum (or frenulum). The rounded basic of the glans is dubbed the corona. The perineal raphe is the noticeable line along the underside that the penis.

The urethra is the last component of the urinary tract and traverses the body spongiosum. The urethral opened is dubbed the meatus and lies on the guideline of the glans penis. That serves as a passage both for urine and semen. Sperm are produced in the testes and stored in the fastened epididymis. Sperm are driven through the vas deferens throughout ejaculation. Fluids are added by the seminal vesicles prior to the vas deferens tote the sperm come the ejaculatory ducts, which join the urethra inside the prostate gland. The prostate as well as the bulbourethral glands include further secretions, climate the semen is expelled with the penis. The raphe is the remarkable ridge between the halves that the penis. The is located on the ventral facet of the penis and runs native the meatus and throughout the scrotum come the perineum (area in between scrotum and also anus).

Homology to the Clitoris

The various parts that the male penis are homologous to components of the mrs clitoris:

Glans that the penis: homologous come the clitoral glansCorpora cavernosa: homologous to the body of the clitorisCorpus spongiosum: homologous come vestibular bulbs beneath the labia minoraScrotum: homologous to the labia minora and also labia majoraForeskin: homologous come the clitoral hood

Penile and Clitoral Structure: This diagram compares the structure of the prick to the clitoris.

The penis As a sexual Organ

An erection is the stiffening and also rising of the prick that facilitates sex-related arousal, though it can likewise happen in nonsexual situations. The primary physiological device that brings about an erection is the autonomic dilation that arteries providing blood come the penis. This allows an ext blood to to fill the 3 spongy erectile tissue chambers in the penis, bring about it to lengthen and stiffen.

The engorged erectile organization presses against and constricts the veins that lug blood far from the penis. More blood enters 보다 leaves the penis until an equilibrium is got to where an equal volume that blood flows right into the dilated arteries and out that the constricted veins; a continuous erectile dimension is completed at this equilibrium. Although plenty of erect penises allude upwards, the is common and normal for the erect dick to suggest nearly vertically upwards, virtually vertically downwards, or also horizontally forward, relying on the stress and anxiety of the suspensory ligament the holds that in position.

Ejaculation is the ejection of semen native the penis and is normally accompanied through orgasm. A series of muscular contractions delivers semen, containing sperm cells or spermatozoa, native the penis. That is usually the an outcome of sexual stimulation, including prostate stimulation. Ejaculation may take place spontaneously throughout sleep (known as a nocturnal emission or “wet dream”).

Ejaculation has two phases: emission and ejaculation proper. The emission step of the ejaculatory reflex is under control of the sympathetic worried system, if the ejaculatory phase is under the regulate of a spinal reflex at the level the spinal nerves S2 to S4 via the pudendal nerve. A refractory duration succeeds the ejaculation, and sexual stimulation comes before it. Anejaculation is the condition of being unable to ejaculate.

Testes Ducts

Testes ducts, which incorporate the seminiferous tubules and vas deferens, are associated in the development or transport of sperm.

Learning Objectives

Differentiate among the ducts of the testes

Key Takeaways

Key PointsCreation the sperm occurs in the seminiferous tubules the the testes.The efferent ducts maintain suitable fluid concentration in the testes and propel sperm to the epididymus.The vas deferens carry the sperm native the epididymus come the urethra.A vasectomy cuts the vas deferens to prevent sperm native entering the urethra and being ejaculated.Key Termsvasectomy: The surgical removal of every or part of the vas deferens, normally as a way of masculine sterilization.peristalsis: A radially symmetry contraction and also relaxation that muscles the propagates in a anterograde (forward) wave down a tube.vas deferens: The duct in the testes that carries semen from the epididymis to the ejaculatory duct.rete testis: one anastomosing network that tubules situated in the hilum of the testicle (mediastinum testis) the carries sperm indigenous the seminiferous tubules come the efferent ducts.

Seminiferous tubules, situated in the testes, are where meiosis occurs and the gametes (spermatozoa) are created. The seminiferous tubules are developed from primitive sex cords indigenous the gonadal ridge. The epithelium of the tubule consists of tall, columnar cells referred to as Sertoli cells. Between the Sertoli cells space spermatogenic cells, which distinguish through meiosis to become sperm cells. There are two species of seminiferous tubules: convoluted, situated toward the lateral side, and also straight, as the tubule come medially to kind ducts the will departure the testis.

Efferent Ducts

The efferent ducts affix the rete testis through the initial ar of the epididymis. There space two an easy types that efferent ductule structure.

Multiple entries right into the epididymis: This kind is checked out in most big mammals. In humans and other big mammals, over there are roughly 15–20 efferent ducts i beg your pardon occupy practically one-third of the head the the epididymis.Single entry: This kind is checked out in most tiny animals such together rodents. This is identified by 3 to six ductules that merge right into a solitary small ductule before entering the epididymis.

The ductuli space unilaminar and also composed of columnar ciliated and nonciliated (absorptive) cells. The ciliated cells stir the luminal fluids, i m sorry may help ensure homogeneous absorb of water native the fluid produced by the testis. This results in rise in the concentration of luminal sperm. The epithelium is surrounding by a tape of smooth muscle the helps to propel the sperm towards the epididymis.

The ductus (vas) deferens, likewise called the sperm duct, extend from the epididymis on every side that the scrotum right into the abdominal muscle cavity with the inguinal canal, an opening in the abdominal wall surface for the spermatic cord. The spermatic cord is a connective organization sheath that contains the vas deferens, testicular blood vessels, and also nerves.

The smooth muscle layer of the vas deferens contract in waves of peristalsis throughout ejaculation. 2 ducts affix the left and right epididymis to the ejaculatory ducts in bespeak to relocate sperm. In humans, each tube is about 30 centimeters (a foot) long,3 come 5 mm in diameter, and also surrounded by smooth muscle. The sperm room transferred native the vas deferens into the urethra, collecting secretions native the masculine accessory sex glands such as the seminal vesicles, prostate gland, and bulbourethral glands, which provide the bulk of semen.

The procedure the deferentectomy, additionally known together a vasectomy, is a an approach of contraception in i beg your pardon the vas deferens room permanently cut, though in some cases it deserve to be reversed. A modern-day procedure the does not encompass cutting the ducts involves injecting one obstructive material into the ductus to block the circulation of sperm. Research study in male contraception has concentrated primarily ~ above the vas deferens v the usage of the intra-vas device and reversible inhibition the sperm under guidance.

Accessory Sex Glands

The accessory sex glands create seminal fluid and clean and also lubricate the urethra.

Learning Objectives

Describe the features of male accessory sex glands

Key Takeaways

Key PointsSeminal glands save on computer seminal motor that create 50–70% of the seminal fluid.The excretory duct of the seminal gland opens into the vas deferens as it enters the prostate gland.Sperm room not in call with the seminal fluid created by the seminal vesicles, possibly to block the progression of sperm from various other males.The prostate secretes 20–30% that the seminal fluid which carries the sperm in the ejaculate.The prostate surrounds the urethra listed below the bladder and also can be felt in a rectal exam.Bulbourethral glands create a pre-ejaculate secretion which lubricates and flushes out the urethra in ready for the sperm.Key Termsbulbourethral gland: an exocrine gland i beg your pardon secretes a clear liquid upon sex-related arousal as pre-ejaculate (or Cowper’s fluid).Lipofuscin: Yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion.prostate: A compound tubuloalveolar exocrine gland of the masculine reproductive mechanism in most mammals.seminal gland: A pair of straightforward tubular glands situated within the pelvisthat secrete fluid that partly composes semen.

The accessory sex glands, consisting of the seminal, prostate glands, and bulbourethral glands, create seminal fluid and clean and also lubricate the urethra.

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Seminal Gland Anatomy

Each seminal gland forms as one outward expansion of the wall surface of ampulla of every vas deferens. They are curled and also folded within the gland and also can spread out out to about 5 cm, yet the unfolded length is roughly 10 cm. The excretory duct that the seminal gland opens into the vas deferens together it start the prostate gland.

Seminal Gland Physiology and Function

The seminal motor secrete a significant proportion the the liquid that at some point becomes semen. Lipofuscin granules native dead epithelial cells give the cheap its yellowish color. About 50–70% the seminal liquid in human beings originates native the seminal vesicles, however is no expelled in the first ejaculate fountain which are dominated by spermatozoa and also zinc-rich prostatic fluid. Seminal vesicle fluid is alkaline, result in person semen through a mildly alkaline pH. This help neutralize the mountain of the vaginal tract, prolonging the expectation of sperm. Acidic ejaculate (pH