Anatomy of the Male Reproductive System

The male reabundant mechanism consists of external (penis, scrotum, epididymus, and testes) and interior (accessory) organs.

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Key Takeaways

Key PointsThe features of the male reproductive mechanism incorporate developing and also carrying sperm, ejaculating sperm into the female reproductive tract, and creating and secreting male hormones.Many of the male reabundant mechanism is located exterior of the body. These outside structures are the penis, scrotum, epididymis, and testes.The internal organs of the male reabundant device are dubbed accessory organs. They encompass the vas deferens, seminal vesicles, prostate gland also, and also bulbourethral glands.Key Termssemen: Contains spermatozoa, proteolytic and various other enzymes, andfructose that promotes spermatozoa survival. It likewise provides a medium for spermmotility.spermatogenesis: The procedure of sperm production within the seminiferous tubules in the testes.testosterone: Steroid hormone produced primarily in the male testes and responsible for the development of male second sex qualities.

The organs of the male refertile system are specialized for three main functions:

To develop, preserve, carry, and also nourish sperm (the male reabundant cells), and also protective liquid ( seguys ).To discharge sperm within the female refertile tract.To produce and secrete male sex hormones.

External Male Sex Organs

Most of the male refertile mechanism is situated external of the man’s body. These exterior frameworks are the penis, scrotum, epididymis, and testes.


Male Reabundant System: Lateral see of male refertile device with organs labeled.

The penis is the male body organ for sexual intercourse and also uricountry. Semen and urine leave the penis through the urethra. The scrotum is a loosened, pouch-choose sack of skin that hangs behind the penis, containing the testes.

The scrotum has a protective attribute, including the maintenance of optimal temperatures for sperm survival and attribute. For sperm advancement, the testes need to keep a temperature slightly cooler than normal body temperature. Special muscles in the wevery one of the scrotum contract and relax in order to move the testes close to the body.

The epididymus is situated at the ago of the testis and connects it to the vas deferens. Its function is to store and carry sperm. The testis is the area for testosterone manufacturing. The coiled arsenal of tubes within the testes are the seminiferous tubules. Within these tubules, spermatogenesis takes place.

Accessory Sex Organs

The inner organs of the male reproductive device are called accessory organs. They include the vas deferens, seminal vesicles, prostate gland also, and bulbourethral (Cowper’s) glands.

Vas deferens: Transporting activities mature sperm to the urethra in preparation for ejaculation.Seminal vesicles: Sac-choose pouches that attach to the vas deferens near the base of the bladder. The vesicles produce molecules such as fructose that serve as power resources for sperm. The seminal vesicle liquid makes up many of the volume of a man’s ejaculate.Prostate gland: A walnut-sized framework located below the urinary bladder in front of the rectum. It contributes additional fluid to the ejaculate that serves as nourishment for sperm.Bulbourethral (Cowper’s) glands: Pea-sized structures located on the sides of the urethra simply listed below the prostate gland also. These glands create a clear, slippery fluid that empties directly right into the urethra. Fluid created by these glands lubricates the urethra and also neutralizes acidity connected through residual urine.


The function of the scrotum is to administer the testes with a chamber of proper temperature for optimal sperm production.

Learning Objectives

Describe the attributes of the scrotum

Key Takeaways

Key PointsMoving the testes ameans from the abdoguys and also raising the exposed surconfront location enable a much faster dispersion of excess heat.If testes were in the abdomales, constant pressure from abdominal muscles would certainly maybe empty the testes and also epididymis prior to sperm were sufficiently mature for fertillization.The attribute of the scrotum appears to be to save the temperature of the testes slightly lower than that of the remainder of the body.Key Termsscrotum: The bag of skin and also muscle that includes the testes in mammals.testosterone: A steroid hormone that plays an essential role in male refertile advancement including the proactivity of second sexual characteristics.epididymis: A narrowhead, tightly-coiled tube where sperm are stored in the time of maturation. It connects the efferent ducts from the rear of each testicle to its vas deferens.

Anatomical Considerations

The scrotum is a dual-chambered suspfinished sack of skin and also smooth muscle that consists of the testes, and is homologous to the labia majora in females. It is an extension of the perineum, and is located between the penis and anus. In human beings and some other mammals, increased testosterone secretion during puberty causes the darkening of the skin and also advance of pubic hair on the scrotum. The left testis is typically reduced than the appropriate, which may feature to stop compression in the occasion of affect. This asymmeattempt may also permit more reliable cooling of the testes.


The attribute of the scrotum shows up to be to store the temperature of the testes slightly reduced than that of the rest of the body. For humans, the temperature must be one or 2 degrees Celsius below body temperature (about 35 degrees Celsius or 95 levels Fahrenheit); greater temperatures may be damaging to sperm count.

The temperature is controlled by scrotal movement of the testes away or towards the body depending upon the eco-friendly temperatures. Moving the testes away from the abdomen and boosting the exposed surconfront location permit a faster dispersion of excess warmth. This is done by indicates of contractivity and relaxation of the cremaster muscle and also the dartos fascia in the scrotum.

However before, temperature regulation might not be the just function of the scrotum. It has actually been suggested that if testes were positioned within the abdominal cavity, they would certainly be subjected to the regular changes in abdominal press that are exerted by the abdominal muscles, resulting in the more quick emptying of the testes and also epididymis of sperm prior to the spermatozoa were matured sufficiently for fertilization. Some mammals (elephants and also marine mammals, for example) do store their testes within the abdomen wbelow tright here may be mechanisms to proccasion this inadvertent emptying.


The scrotum: Image of the outside, muscle, and deep tconcern views of the scrotum.

Key Takeaways

Key PointsThe testes develop the hormones testosterone and also various other androgens.Sperm are created within seminiferous tubules.Leydig cells develop and also secrete male hormones.Sertoli cells aid in the process of spermatogenesis.Key TermsLeydig cells: Also well-known as interstitial cells of Leydig, these are discovered adjacent to the seminiferous tubules in the testicle and also produce testosterone in the presence of luteinizing hormone.follicle-stimulating hormone: Stimulates the expansion and recruitment of immature ovarian follicles in females. In males, it is instrumental for spermatogenesis as it stimulates major spermatocytes to create additional spermatocytes.sertoli cells: Part of the seminiferous tubule that helps in the process of spermatogenesis.Luteinizing hormone: A hormone produced by gonadotropic cells of the anterior pituitary gland. It triggers ovulation and advancement of the corpus luteum in females and also stimulates Leydig cell production of testosterone in males.testes: Also referred to as testicles, the male gonads in animals.

Testicle: A diagram of the major components of an adult huguy testis, consisting of 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 of 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 of tunica vaginalis.

The testis is the male gonad in animals. Like the ovaries to which they are homologous, testes are components of both the reproductive mechanism and the endocrine device. Thee testes create sperm (spermatogenesis) and also androgens, mainly testosterone. Both functions of the testis are influenced by gonadotropic hormones created by the anterior pituitary gland also. Luteinizing hormone results in testosterone release. The existence of both testosterone and also follicle-stimulating hormone (FSH) is required to assistance spermatogenesis.

Ala lot of all healthy and balanced male vertebrates have actually 2 testes. In mammals, the testes are regularly included within an extension of the abdoguys dubbed the scrotum. In mammals via exterior testes, it is a lot of prevalent for one testicle to hang lower than the other. While the size of the testis varies, it is estimated that 21.9% of males have actually one higher-positioned testis, while 27.3% of males have actually reported equally-positioned testicles.

The difficult membranous shell referred to as the tunica albuginea consists of exceptionally fine coiled tubes called seminiferous tubules. These are lined through a layer of germ cells that develop into sperm cells (likewise known as spermatozoa or male gametes) from puberty right into old age. The arising sperm travels through the seminiferous tubules to the rete testis situated in the mediastinum testis, to the efferent ducts, and also then to the epididymis wright here newly-produced sperm cells mature. The sperm moves right into the vas deferens and is ultimately expelled via the urethra, via the urethral orifice via muscular contractions.

Leydig cells situated between seminiferous tubules create and also secrete testosterone and other androgens crucial for sexual advance and puberty, consisting of second sexual qualities such as facial hair and sexual behavior. They additionally support libiexecute, spermatogenesis, and also erectile function. In enhancement, testosterone controls testicular volume. The sertoli cells are the testes’ somatic cells, vital for testis development and also spermatogenesis.

Inside the Person Testes: Diagram illustprices the scrotum with a portion of the spanning rerelocated to screen the testis.

Key Takeaways

Key PointsThe major structure of the penis is created by columns of corpus cavernoamount and spongiosum tissue.The head of the penis, dubbed the glans, contains the opening for the urethral duct, the passage for urine and seminal fluid.The penis and also clitoris (discovered in women) are homologous organs.Blood engorgement of penile tissue reasons the penis to come to be erect, facilitating sexual intercourse.Ejaculation is the release of sperm, which propels the sperm into the vaginal canal when it occurs throughout intercourse.Key Termsglans: The vascular body which develops the apex of the penis.penis: The male sexual body organ for copulation and urination; the tubular percentage of the male genitalia (excluding the scrotum).intromittent organ: A term for a male external body organ that delivers sperm throughout copulation.clitdental glans: Highly innervated component of the clitoris that exists at the pointer of the clitoral body as a fibrovascular cap.ejaculation: The forcible ejection of semales from the mammalian urethra, a reflex in response to sexual stimulation.

The penis is an intromittent body organ of male pets through reproductive and urinary functions. Unchoose many kind of various other species, the human penis has no baculum, or erectile bone. Instead, it relies totally on engorgement through blood to achieve erection. The huguy penis cannot be withdrawn right into the groin, andis bigger than that of any various other primate, especially in regards to propercentage to body mass.

Human Penis: This is a diagram of a huguy penis through its parts labeled.

Parts of the Penis

The huguy penis is made up of 3 columns of tissue: 2 corpora cavernosa that lie beside each other on the dorsal side and also a corpus spongiosum that lies in between the corpora cavernosa on the ventral side. The glans penis is the bulbous end of the penis formed by the corpus spongiosum. It supports the foreskin (prepuce) that retracts to disclose the glans. The area on the underside of the penis, wbelow the foreskin is attached, is called the frenum (or frenulum). The rounded base of the glans is referred to as the corona. The perineal raphe is the noticeable line along the underside of the penis.

The urethra is the last part of the urinary tract and also traverses the corpus spongioamount. The urethral opening is called the meatus and also lies on the guideline of the glans penis. It serves as a passage both for urine and semales. Sperm are developed in the testes and also stored in the attached epididymis. Sperm are moved through the vas deferens in the time of ejaculation. Fluids are added by the seminal vesicles before the vas deferens carries the sperm to the ejaculatory ducts, which join the urethra inside the prostate gland also. The prostate and the bulbourethral glands add additionally secretions, then the seguys is expelled via the penis. The raphe is the noticeable ridge in between the halves of the penis. It is located on the ventral aspect of the penis and runs from the meatus and also throughout the scrotum to the perineum (location in between scrotum and also anus).

Homology to the Clitoris

The various components of the male penis are homologous to components of the female clitoris:

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

Penile and also Clitdental Structure: This diagram compares the framework of the penis to the clitoris.

The Penis As a Sexual Organ

An erection is the stiffening and also climbing of the penis that facilitates sex-related arousal, though it deserve to likewise happen in nonsexual instances. The primary physiological device that brings about an erection is the autonomic dilation of arteries giving blood to the penis. This permits more blood to fill the 3 spongy erectile tconcern chambers in the penis, causing it to lengthen and also stiffen.

The engorged erectile tconcern presses versus and also constricts the veins that bring blood amethod from the penis. More blood enters than leaves the penis until an equilibrium is got to wright here an equal volume of blood flows into the dilated arteries and also out of the constricted veins; a constant erectile size is achieved at this equilibrium. Although many erect penises point upwards, it is common and normal for the erect penis to allude virtually vertically upwards, practically vertically downwards, or also horizontally forward, depending upon the tension of the suspensory ligament that holds it in position.

Ejaculation is the ejection of seguys from the penis and is commonly accompanied by orgasm. A series of muscular contractions delivers semen, containing sperm cells or spermatozoa, from the penis. It is commonly the outcome of sexual stimulation, consisting of prostate stimulation. Ejaculation might occur spontaneously during sleep (known as a nocturnal emission or “wet dream”).

Ejaculation has 2 phases: emission and ejaculation proper. The emission phase of the ejaculatory reflex is under manage of the sympathetic nervous system, while the ejaculatory phase is under the manage of a spinal reflex at the level of spinal nerves S2 to S4 using the pudendal nerve. A refractory period succeeds the ejaculation, and sexual stimulation precedes it. Anejaculation is the condition of being unable to ejaculate.

Testes Ducts

Testes ducts, which include the seminiferous tubules and also vas deferens, are associated in the creation or transportation of sperm.

Learning Objectives

Differentiate among the ducts of the testes

Key Takeaways

Key PointsCreation of sperm occurs in the seminiferous tubules of the testes.The efferent ducts preserve appropriate fluid concentration in the testes and propel sperm to the epididymus.The vas deferens bring the sperm from the epididymus to the urethra.A vasectomy cuts the vas deferens to proccasion sperm from entering the urethra and also being ejaculated.Key Termsvasectomy: The surgical removal of all or part of the vas deferens, typically as a way of male sterilization.peristalsis: A radially symmetrical contractivity and relaxation of muscles that propaentrances in a anterograde (forward) wave down a tube.vas deferens: The duct in the testes that carries semales from the epididymis to the ejaculatory duct.rete testis: An anastomosing netoccupational of tubules located in the hilum of the testicle (mediastinum testis) that carries sperm from the seminiferous tubules to the efferent ducts.

Seminiferous tubules, situated in the testes, are where meiosis occurs and the gametes (spermatozoa) are produced. The seminiferous tubules are developed from primitive sex cords from the gonadal ridge. The epithelium of the tubule consists of tall, columnar cells referred to as Sertoli cells. Between the Sertoli cells are spermatogenic cells, which identify through meiosis to come to be sperm cells. Tright here are 2 types of seminiferous tubules: convoluted, located toward the lateral side, and straight, as the tubule comes medially to develop ducts that will departure the testis.

Efferent Ducts

The efferent ducts connect the rete testis through the initial section of the epididymis. There are 2 standard types of efferent ductule structure.

Multiple entries right into the epididymis: This form is checked out in most huge mammals. In human beings and other large mammals, tbelow are around 15–20 efferent ducts which occupy almost one-third of the head of the epididymis.Single entry: This form is seen in most tiny pets such as rodents. This is characterized by three to six ductules that merge right into a solitary little ductule before entering the epididymis.

The ductuli are unilaminar and also created of columnar ciliated and also nonciliated (absorptive) cells. The ciliated cells stir the luminal fluids, which may help ensure homogeneous absorption of water from the fluid created by the testis. This results in an increase in the concentration of luminal sperm. The epithelium is surrounded by a band also of smooth muscle that helps to propel the sperm towards the epididymis.

The ductus (vas) deferens, likewise referred to as the sperm duct, extend from the epididymis on each side of the scrotum right into the abdominal cavity via the inguinal canal, an opening in the abdominal wall for the spermatic cord. The spermatic cord is a connective tissue sheath that includes the vas deferens, testicular blood vessels, and nerves.

The smooth muscle layer of the vas deferens contracts in waves of peristalsis in the time of ejaculation. Two ducts attach the left and also ideal epididymis to the ejaculatory ducts in order to move sperm. In people, each tube is about 30 centimeters (a foot) long,3 to 5 mm in diameter, and also surrounded by smooth muscle. The sperm are transferred from the vas deferens into the urethra, collecting secretions from the male accessory sex glands such as the seminal vesicles, prostate gland, and bulbourethral glands, which administer the mass of semales.

The procedure of deferentectomy, likewise well-known as a vasectomy, is an approach of contraception in which the vas deferens are permanently cut, though in some instances it can be reversed. A modern procedure that does not incorporate cutting the ducts involves injecting an obstructive material right into the ductus to block the flow of sperm. Research in male contraception has actually focused mainly on the vas deferens through the usage of the intra-vas device and also reversible inhibition of sperm under guidance.

Accessory Sex Glands

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

Learning Objectives

Describe the attributes of male accessory sex glands

Key Takeaways

Key PointsSeminal glands contain seminal vesicles that produce 50–70% of the seminal liquid.The excretory duct of the seminal gland also opens into the vas deferens as it enters the prostate gland.Sperm are not in contact via the seminal fluid created by the seminal vesicles, maybe to block the development of sperm from various other males.The prostate secretes 20–30% of the seminal liquid which carries the sperm in the ejaculate.The prostate surrounds the urethra below the bladder and also can be felt in a rectal exam.Bulbourethral glands produce a pre-ejaculate secretion which lubricates and also flushes out the urethra in preparation for the sperm.Key Termsbulbourethral gland: An exocrine gland also which secretes a clear liquid upon sexual arousal as pre-ejaculate (or Cowper’s fluid).Lipofuscin: Yellow-brown pigment granules created of lipid-containing residues of lysosomal digestion.prostate: A compound tubuloalveolar exocrine gland also of the male reabundant device in many mammals.seminal gland: A pair of basic tubular glands located within the pelvisthat secrete fluid that partially composes seguys.

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

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Seminal Gland Anatomy

Each seminal gland also forms as an external development of the wall of ampulla of each vas deferens. They are curled and also folded within the gland also and also have the right to spcheck out out to around 5 cm, however the unravelled size is around 10 cm. The excretory duct of the seminal gland also opens up into the vas deferens as it enters the prostate gland.

Seminal Gland Physiology and Function

The seminal vesicles secrete a significant proportion of the liquid that inevitably becomes semales. Lipofuscin granules from dead epithelial cells provide the secretion its yellowish shade. About 50–70% of seminal fluid in human beings originates from the seminal vesicles, yet is not expelled in the first ejaculate fractions which are dominated by spermatozoa and also zinc-wealthy prostatic liquid. Seminal vesicle fluid is alkaline, bring about human semales with a mildly alkaline pH. This helps neutralize the acidity of the vaginal tract, expanding the lifeexpectations of sperm. Acidic ejaculate (pH