Anatomy the the masculine Reproductive System

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

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Key Takeaways

Key PointsThe functions of the male reproductive system incorporate producing and transporting sperm, ejaculating sperm into the mrs reproductive tract, and also producing and also secreting male hormones.Most the the masculine reproductive device is located exterior of the body. These outside structures room the penis, scrotum, epididymis, and also testes.The interior organs the the male reproductive system are called accessory organs. They incorporate the vas deferens, seminal vesicles, prostate gland, and bulbourethral glands.Key Termssemen: has spermatozoa, proteolytic and also other enzymes, andfructose the promotes spermatozoa survival. It also provides a medium for spermmotility.spermatogenesis: The process of sperm production within the seminiferous tubules in the testes.testosterone: Steroid hormone produced primarily in the male testes and responsible because that the development of male secondary sex characteristics.

The guts of the masculine reproductive system are specialized for three major functions:

To produce, maintain, transport, and also nourish sperm (the masculine reproductive cells), and also protective liquid ( semen ).To discharge sperm within the female reproductive tract.To produce and secrete masculine sex hormones.

External male Sex Organs

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


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Male Reproductive System: Lateral view of masculine reproductive device with organs labeled.


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

The scrotum has actually a security function, consisting of the maintenance of optimal temperatures for sperm survival and also function. For sperm development, the testes must maintain a temperature slightly cooler than common body temperature. One-of-a-kind muscles in the wall surface of the scrotum contract and relax in stimulate to move the testes near the body.

The epididymus is situated at the back of the testis and connects it come the vas deferens. Its function is come store and carry sperm. The testis is the location for testosterone production. The coiled collection of tubes in ~ the testes are the seminiferous tubules. Within these tubules, spermatogenesis take away place.

Accessory Sex Organs

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

Vas deferens: Transports mature sperm to 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 develop molecules such as fructose that serve as power sources for sperm. The seminal vesicle fluid makes up most of the volume the a man’s ejaculate.Prostate gland: A walnut-sized framework located listed below the urinary bladder in former of the rectum. The contributes additional fluid to the ejaculate that serves as nourishment for sperm.Bulbourethral (Cowper’s) glands: Pea-sized structures located on the political parties of the urethra just listed below the prostate gland. These glands produce a clear, slippery fluid that empties directly into the urethra. Fluid produced by this glands lubricates the urethra and also neutralizes acidity connected with residual urine.

Scrotum

The function of the scrotum is to administer the testes through a chamber of appropriate temperature because that optimal sperm production.


Learning Objectives

Describe the functions of the scrotum


Key Takeaways

Key PointsMoving the testes away from the abdomen and also increasing the exposed surface ar area enable a quicker dispersion of overfill heat.If testes to be in the abdomen, continuous pressure from abdominal muscles would probably empty the testes and also epididymis before sperm to be sufficiently mature for fertillization.The role of the scrotum appears to it is in to store the temperature of the testes slightly lower than that of the rest of the body.Key Termsscrotum: The bag the skin and also muscle that has the testes in mammals.testosterone: A steroid hormone the plays a an essential role in male reproductive development including the promo of secondary sexual characteristics.epididymis: A narrow, tightly-coiled tube whereby sperm space stored throughout maturation. The connects the efferent ducts indigenous the rear of every testicle come its vas deferens.

Anatomical Considerations

The scrotum is a dual-chambered suspended bag of skin and smooth muscle that consists of the testes, and is homologous come the labia majora in females. It is an extension of the perineum, and also is located between the penis and also anus. In humans and also some various other mammals, boosted testosterone secretion during puberty causes the darkening that the skin and breakthrough of pubic hair ~ above the scrotum. The left testis is usually reduced than the right, i m sorry may duty to stop compression in the event of impact. This asymmetry may likewise allow more effective cooling of the testes.

Function

The role of the scrotum appears to it is in to store the temperature the the testes slightly lower than that of the remainder of the body. For person beings, the temperature must be one or two levels Celsius below body temperature (around 35 levels Celsius or 95 degrees Fahrenheit); greater temperatures may be damaging come sperm count.

The temperature is managed by scrotal movement of the testes far or in the direction of the body depending on the environmental temperatures. Moving the testes far from the abdomen and also increasing the exposed surface ar area enable a faster dispersion of excess heat. This is excellent by method of contraction and also relaxation of the cremaster muscle and the dartos fascia in the scrotum.

However, temperature regulation may not be the only duty of the scrotum. It has been argued that if testes were situated within the abdominal cavity, they would be subjected to the regular alters in abdominal pressure that are exerted through the ab muscles, resulting in the much more rapid emptying the the testes and epididymis of sperm prior to the spermatozoa to be matured sufficiently for fertilization. Some mammals (elephants and marine mammals, for example) carry out keep their testes within the abdomen whereby there might be instrument to avoid this inadvertent emptying.


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


Key Takeaways

Key PointsThe testes create the hormones testosterone and other androgens.Sperm are created within seminiferous tubules.Leydig cell produce and secrete masculine hormones.Sertoli cells help in the procedure of spermatogenesis.Key TermsLeydig cells: likewise known together interstitial cells of Leydig, these are found nearby to the seminiferous tubules in the testicle and produce testosterone in the presence of luteinizing hormone.follicle-stimulating hormone: Stimulates the growth and recruitment that immature ovarian follicles in females. In males, it is an essential for spermatogenesis together it stimulates primary spermatocytes to form secondary spermatocytes.sertoli cells: part of the seminiferous tubule the helps in the process of spermatogenesis.Luteinizing hormone: A hormone produced by gonadotropic cell of the anterior pituitary gland. It triggers ovulation and development of the body luteum in females and also stimulates Leydig cell production of testosterone in males.testes: likewise referred to as testicles, the masculine gonads in animals.

Testicle: A chart of the significant components of an adult human being testis, including the adhering to 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 that epididymis,10. Vas deferens, 11a. Tunica vaginalis (parietal lamina), 11b. Tunica vaginalis (visceral lamina), and also 12. Cavity that tunica vaginalis.


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

Almost all healthy and balanced male vertebrates have two testes. In mammals, the testes space often consisted of within an extension of the abdomen called the scrotum. In mammals with outside testes, the is most typical for one testicle to hang lower than the other. When the dimension of the testis varies, that is approximated that 21.9% the men have actually one higher-positioned testis, while 27.3% that men have reported equally-positioned testicles.

The tough membranous shell dubbed the tunica albuginea contains an extremely fine coiled tubes dubbed seminiferous tubules. These room lined through a class of germ cells that build into sperm cells (also known as spermatozoa or male gametes) native puberty into old age. The arising sperm travels with the seminiferous tubules come the rete testis located in the mediastinum testis, come the efferent ducts, and then to the epididymis wherein newly-created sperm cell mature. The sperm moves right into the vas deferens and is at some point expelled v the urethra, via the urethral orifice v muscular contractions.

Leydig cells located in between seminiferous tubules produce and also secrete testosterone and also other androgens vital for sexual advancement and puberty, including second sexual characteristics such together facial hair and also sexual behavior. They also support libido, spermatogenesis, and erectile function. In addition, testosterone controls testicular volume. The sertoli cells space the testes’ somatic cells, vital for testis development and spermatogenesis.


Inside the human Testes: chart illustrates the scrotum with a section of the covering removed to screen the testis.


Key Takeaways

Key PointsThe significant structure the the prick is formed by columns of corpus cavernosum and spongiosum tissue.The head the the penis, called the glans, consists of the opening for the urethral duct, the passage for urine and also seminal fluid.The penis and also clitoris (found in women) space homologous organs.Blood engorgement that penile tissue causes the penis to become erect, facilitating sexual intercourse.Ejaculation is the release of sperm, i beg your pardon propels the sperm right into the vaginal canal when it occurs during intercourse.Key Termsglans: The vascular body which creates the apex of the penis.penis: The male sexual organ for copulation and urination; the tubular section of the masculine genitalia (excluding the scrotum).intromittent organ: A term for a male exterior organ the delivers sperm during copulation.clitoral glans: very innervated component of the clitoris that exists at the reminder of the clitoral body together a fibrovascular cap.ejaculation: The forcible ejection of semen from the mammalian urethra, a reflex in response to sex-related stimulation.

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


Human Penis: This is a diagram of a human cock with its components labeled.


Parts the the Penis

The human cock is consisted of of three columns of tissue: two corpora cavernosa the lie alongside each various other on the dorsal side and a body spongiosum the lies between the corpora cavernosa on the ventral side. The glans cock is the bulbous end of the penis formed through the corpus spongiosum. It supports the foreskin (prepuce) that retracts to reveal the glans. The area top top the underside of the penis, wherein 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 remarkable line along the underside the the penis.

The urethra is the last part of the urinary tract and traverses the corpus spongiosum. The urethral opening is called the meatus and lies top top the pointer of the glans penis. That serves as a i both for urine and also semen. Sperm are developed in the testes and stored in the enclosed epididymis. Sperm are driven through the vas deferens during ejaculation. Fluids are added by the seminal vesicles prior to the vas deferens dead the sperm come the ejaculatory ducts, which sign up with 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 noticeable ridge between the halves the the penis. That is situated on the ventral element of the penis and runs from the meatus and throughout the scrotum come the perineum (area in between scrotum and anus).

Homology come the Clitoris

The various parts that the male dick are homologous to components of the woman clitoris:

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

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


The dick As a sex-related Organ

An erection is the stiffening and rising of the cock that facilitates sex-related arousal, though it can additionally happen in nonsexual situations. The primary physiological device that brings around an erection is the autonomic dilation the arteries giving blood come the penis. This allows an ext blood to to fill the 3 spongy erectile organization chambers in the penis, resulting in it come lengthen and stiffen.

The engorged erectile tissue presses against and constricts the veins that lug blood far from the penis. More blood enters 보다 leaves the penis until one equilibrium is got to where an same volume of blood flows into the dilated arteries and also out the the constricted veins; a consistent erectile dimension is achieved at this equilibrium. Although plenty of erect penises allude upwards, that is common and also normal because that the erect prick to allude nearly vertically upwards, virtually vertically downwards, or even horizontally forward, relying on the tension of the suspensory ligament that holds it in position.

Ejaculation is the ejection the semen indigenous the penis and is commonly accompanied by orgasm. A series of muscular contractions it is intended semen, comprise sperm cell or spermatozoa, native the penis. The is usually the an outcome of sex-related stimulation, including prostate stimulation. Ejaculation may occur spontaneously throughout sleep (known as a nocturnal emission or “wet dream”).

Ejaculation has two phases: emission and also ejaculation proper. The emission step of the ejaculatory reflex is under regulate of the sympathetic worried system, when the ejaculatory step is under the regulate of a spinal reflex in ~ the level that spinal nerves S2 to S4 via the pudendal nerve. A refractory period succeeds the ejaculation, and also sexual stimulation comes before it. Anejaculation is the problem of gift unable come ejaculate.


Testes Ducts

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


Learning Objectives

Differentiate amongst the ducts of the testes


Key Takeaways

Key PointsCreation of sperm occurs in the seminiferous tubules the the testes.The efferent ducts maintain appropriate fluid concentration in the testes and propel sperm to the epididymus.The vas deferens bring the sperm indigenous the epididymus come the urethra.A vasectomy cut the vas deferens to protect against sperm native entering the urethra and being ejaculated.Key Termsvasectomy: The operation removal of every or component of the vas deferens, commonly as a way of male sterilization.peristalsis: A radially symmetry contraction and also relaxation the muscles that propagates in a anterograde (forward) wave under a tube.vas deferens: The duct in the testes that carries semen indigenous the epididymis come the ejaculatory duct.rete testis: one anastomosing network of tubules situated in the hilum the the testicle (mediastinum testis) the carries sperm from the seminiferous tubules come the efferent ducts.

Seminiferous tubules, situated in the testes, space where meiosis occurs and also the gametes (spermatozoa) space created. The seminiferous tubules are formed from primitive sex cords native the gonadal ridge. The epithelium of the tubule consists of tall, columnar cells dubbed Sertoli cells. In between the Sertoli cells are spermatogenic cells, which identify through meiosis to end up being sperm cells. There space two types of seminiferous tubules: convoluted, situated toward the lateral side, and straight, as the tubule comes medially to type ducts that will leave the testis.

Efferent Ducts

The efferent ducts connect the rete testis v the initial section of the epididymis. There are two an easy types of efferent ductule structure.

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

The ductuli space unilaminar and composed the columnar ciliated and nonciliated (absorptive) cells. The ciliated cell stir the luminal fluids, i beg your pardon may help ensure homogeneous absorb of water indigenous the fluid developed by the testis. This outcomes in rise in the concentration of luminal sperm. The epithelium is surrounding by a band of smooth muscle that helps to propel the sperm toward the epididymis.



The ductus (vas) deferens, likewise called the sperm duct, expand from the epididymis on every side of the scrotum right into the ab cavity through the inguinal canal, an opened in the abdominal wall for the spermatic cord. The spermatic cord is a connective tissue sheath that has the vas deferens, testicular blood vessels, and also nerves.

The smooth muscle great of the vas deferens contracts in waves of peristalsis throughout ejaculation. Two ducts affix the left and also right epididymis come the ejaculatory ducts in stimulate to move sperm. In humans, each pipe is around 30 centimeters (a foot) long,3 to 5 mm in diameter, and surrounded by smooth muscle. The sperm are transferred native the vas deferens right into the urethra, collecting secretions from the male accessory sex glands such together the seminal vesicles, prostate gland, and bulbourethral glands, which carry out the mass of semen.

The procedure that deferentectomy, also known as a vasectomy, is a an approach of contraception in i m sorry the vas deferens are permanently cut, despite in some situations it have the right to be reversed. A modern-day procedure that does not incorporate cutting the ducts entails injecting an obstructive material right into the ductus to block the circulation of sperm. Research study in male contraception has focused primarily ~ above the vas deferens through the usage of the intra-vas an equipment and reversible inhibition the sperm under guidance.


Accessory Sex Glands

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


Learning Objectives

Describe the functions of masculine accessory sex glands


Key Takeaways

Key PointsSeminal glands save on computer seminal motor that create 50–70% of the seminal fluid.The excretory duct the the seminal gland opens right into the vas deferens as it enters the prostate gland.Sperm room not in contact with the seminal fluid created by the seminal vesicles, possibly to block the progression of sperm from other males.The prostate secretes 20–30% that the seminal liquid which tote the sperm in the ejaculate.The prostate surrounding the urethra below the bladder and can it is in felt in a rectal exam.Bulbourethral glands create a pre-ejaculate cheap which lubricates and also flushes out the urethra in preparation for the sperm.Key Termsbulbourethral gland: one exocrine gland which secretes a clear liquid upon sex-related arousal together pre-ejaculate (or Cowper’s fluid).Lipofuscin: Yellow-brown pigment granules created of lipid-containing residual water of lysosomal digestion.prostate: A compound tubuloalveolar exocrine gland that the male reproductive system in many mammals.seminal gland: A pair of basic tubular glands located within the pelvisthat secrete liquid that partially composes semen.

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

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Seminal Gland Anatomy

Each seminal gland creates as an outward expansion of the wall of ampulla of every vas deferens. They space curled and folded in ~ the gland and also can spread out to about 5 cm, yet the unfolded size is approximately 10 cm. The excretory duct that the seminal gland opens right into the vas deferens together it start the prostate gland.

Seminal Gland Physiology and Function

The seminal vesicles secrete a far-reaching proportion the the fluid that ultimately becomes semen. Lipofuscin granules native dead epithelial cells provide the cheap its yellowish color. About 50–70% the seminal liquid in humans originates indigenous the seminal vesicles, but is no expelled in the first ejaculate fractions which are dominated by spermatozoa and zinc-rich prostatic fluid. Seminal vesicle fluid is alkaline, resulting in person semen through a mildly alkaline pH. This helps neutralize the mountain of the vaginal tract, expanding the expectancy of sperm. Acidic ejaculate (pH