Anatomy of the male Reproductive System

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

You are watching: The interstitial endocrine cells that produce testosterone are located ________.

Key Takeaways

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

The offal of the male reproductive device are specialized for three main functions:

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

External male Sex Organs

Most the the male reproductive system is located outside of the man’s body. These outside structures room the penis, scrotum, epididymis, and also testes.


Male Reproductive System: Lateral view of male reproductive system with guts labeled.

The prick is the male organ for sexual intercourse and also urination. Semen and also urine leaving the cock through the urethra. The scrotum is a loose, pouch-like sack of skin that hangs behind the penis, comprise the testes.

The scrotum has actually a protective function, consisting of the maintenance of optimal temperatures for sperm survival and function. For sperm development, the testes must preserve a temperature contempt cooler than common body temperature. Special muscles in the wall surface of the scrotum contract and relax in order to move the testes near the body.

The epididymus is situated at the earlier of the testis and connects it come the vas deferens. Its duty is come store and carry sperm. The testis is the place for testosterone production. The coiled arsenal of tubes within the testes room the seminiferous tubules. Within this tubules, spermatogenesis bring away place.

Accessory Sex Organs

The inner organs of the masculine reproductive device are referred to as accessory organs. They encompass the vas deferens, seminal vesicles, prostate gland, and also bulbourethral (Cowper’s) glands.

Vas deferens: Transports tires sperm to the urethra in ready for ejaculation.Seminal vesicles: Sac-like pouches that connect to the vas deferens near the basic of the bladder. The vesicles develop molecules such as furustos that serve as power sources for sperm. The seminal vesicle liquid makes up many of the volume the a man’s ejaculate.Prostate gland: A walnut-sized structure located below the urinary bladder in front of the rectum. It contributes extr fluid come the ejaculate the serves together nourishment for sperm.Bulbourethral (Cowper’s) glands: Pea-sized structures located on the political parties of the urethra just below the prostate gland. These glands produce a clear, slippery fluid that empties directly into the urethra. Fluid created by this glands lubricates the urethra and neutralizes acidity associated with residual urine.


The purpose of the scrotum is to carry out the testes with a chamber of appropriate temperature for optimal sperm production.

Learning Objectives

Describe the functions of the scrotum

Key Takeaways

Key PointsMoving the testes far from the abdomen and increasing the exposed surface ar area enable a quicker dispersion of overabundance heat.If testes were in the abdomen, consistent pressure from ab muscles would maybe empty the testes and also epididymis before sperm were sufficiently mature for fertillization.The function of the scrotum appears to it is in to keep the temperature that the testes slightly reduced than the of the rest of the body.Key Termsscrotum: The bag of skin and muscle that includes the testes in mammals.testosterone: A steroid hormone that plays a an essential role in male reproductive development including the promotion of secondary sexual characteristics.epididymis: A narrow, tightly-coiled tube wherein sperm room stored during maturation. That connects the efferent ducts indigenous the rear of every testicle to its vas deferens.

Anatomical Considerations

The scrotum is a dual-chambered suspended sack of skin and smooth muscle that has the testes, and also is homologous to the labia majora in females. The is an expansion of the perineum, and is located between the penis and anus. In humans and some various other mammals, increased testosterone secretion throughout puberty causes the darkening the the skin and advance of pubic hair top top the scrotum. The left testis is usually lower than the right, which may duty to protect against compression in the occasion of impact. This asymmetry may also allow an ext effective cooling the the testes.


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

The temperature is regulated by scrotal motion of the testes away or in the direction of the body depending on the eco-friendly temperatures. Relocating the testes away from the abdomen and increasing the exposed surface area permit a quicker dispersion of excess heat. This is done by means of contraction and also relaxation of the cremaster muscle and also the dartos fascia in the scrotum.

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


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

Key Takeaways

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

Testicle: A chart of the major components of one adult person testis, consisting of the following 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 that epididymis, 9b. Body of epididymis, 9.c Tail the 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. Prefer the ovaries come which they are homologous, testes are materials of both the reproductive system and the endocrine system. Thee testes produce sperm (spermatogenesis) and androgens, mostly testosterone. Both attributes of the testis are affected by gonadotropic hormones created by the anterior pituitary gland. Luteinizing hormone outcomes in testosterone release. The existence of both testosterone and follicle-stimulating hormone (FSH) is needed to assistance spermatogenesis.

Almost all healthy male vertebrates have two testes. In mammals, the testes space often had within an extension of the abdomen called the scrotum. In mammals with exterior testes, it is most usual for one testicle to hang reduced than the other. If the dimension of the testis varies, it is estimated that 21.9% that men have actually one higher-positioned testis, when 27.3% the men have reported equally-positioned testicles.

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

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

Inside the person Testes: diagram illustrates the scrotum with a portion of the covering gotten rid of to display screen the testis.

Key Takeaways

Key PointsThe major structure of the penis is created by columns of corpus cavernosum and also spongiosum tissue.The head that the penis, called the glans, has the opening for the urethral duct, the passage because that urine and also seminal fluid.The penis and clitoris (found in women) are homologous organs.Blood engorgement the penile tissue causes the dick to come to be erect, facilitating sex-related intercourse.Ejaculation is the release of sperm, i m sorry propels the sperm right into the vaginal canal when it occurs throughout intercourse.Key Termsglans: The vascular human body which forms the apex the the penis.penis: The male sexual body organ for copulation and also urination; the tubular part of the male genitalia (excluding the scrotum).intromittent organ: A term because that a male external organ the delivers sperm during copulation.clitoral glans: extremely innervated component of the clitoris the exists at the tip of the clitoral body as a fibrovascular cap.ejaculation: The forcible ejection the semen native the mammalian urethra, a reflex in an answer to sexual stimulation.

The prick is one intromittent body organ of male pets with reproductive and also urinary functions. Unlike numerous other species, the human penis has no baculum, or erectile bone. Instead, the relies completely on engorgement v blood to achieve erection. The human penis cannot be withdrawn right into the groin, andis bigger than the of any type of other primate, specifically in regards come proportion to human body mass.

Human Penis: This is a diagram of a human prick with its parts labeled.

Parts the the Penis

The human dick is made up of three columns that tissue: two corpora cavernosa that lie next to each various other on the dorsal side and also a corpus spongiosum the lies in between the corpora cavernosa ~ above the ventral side. The glans cock is the bulbous end of the prick formed by the body spongiosum. It support the foreskin (prepuce) that retracts to reveal the glans. The area top top the underside of the penis, whereby the foreskin is attached, is called the frenum (or frenulum). The rounded basic of the glans is dubbed the corona. The perineal raphe is the remarkable line follow me the underside that the penis.

The urethra is the last part of the urinary tract and also traverses the body spongiosum. The urethral opened is referred to as the meatus and also lies top top the pointer of the glans penis. That serves together a i both for urine and also semen. Sperm are produced in the testes and stored in the fastened epididymis. Sperm are pushed 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 join the urethra within the prostate gland. The prostate as well as the bulbourethral glands add further secretions, climate the semen is expelled through the penis. The raphe is the noticeable ridge in between the halves of the penis. The is situated on the ventral aspect of the penis and also runs indigenous the meatus and throughout the scrotum come the perineum (area between scrotum and also anus).

Homology come the Clitoris

The assorted parts the the male prick are homologous to parts of the female clitoris:

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

Penile and also Clitoral 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 rising that the penis that facilitates sex-related arousal, despite it can also happen in nonsexual situations. The primary physiological system that brings about an erection is the autonomic dilation the arteries giving blood to the penis. This allows an ext blood to fill the three spongy erectile organization chambers in the penis, leading to it come lengthen and also stiffen.

The engorged erectile organization presses against and constricts the veins that lug blood far from the penis. Much more blood enters 보다 leaves the cock until an 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 completed at this equilibrium. Although countless erect penises suggest upwards, that is common and normal because that the erect cock to point nearly vertically upwards, nearly vertically downwards, or also horizontally forward, relying on the anxiety of the suspensory ligament that holds that in position.

Ejaculation is the ejection the semen indigenous the penis and also is generally accompanied through orgasm. A collection of muscular contractions it is intended semen, comprise sperm cells or spermatozoa, indigenous the penis. That is typically the result of sex-related stimulation, including prostate stimulation. Ejaculation may happen spontaneously throughout sleep (known as a nocturnal emissions or “wet dream”).

Ejaculation has two phases: emission and also ejaculation proper. The emission phase of the ejaculatory reflex is under manage of the sympathetic worried system, while the ejaculatory step is under the control 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 problem of being unable to ejaculate.

Testes Ducts

Testes ducts, which encompass the seminiferous tubules and also vas deferens, are involved in the development or transportation of sperm.

Learning Objectives

Differentiate among the ducts that the testes

Key Takeaways

Key PointsCreation that sperm occurs in the seminiferous tubules of the testes.The efferent ducts maintain appropriate fluid concentration in the testes and also propel sperm come the epididymus.The vas deferens bring the sperm native 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 part of the vas deferens, commonly as a way of male sterilization.peristalsis: A radially symmetry contraction and relaxation that muscles that propagates in a anterograde (forward) wave down a tube.vas deferens: The duct in the testes that carries semen native the epididymis come the ejaculatory duct.rete testis: an anastomosing network of tubules situated in the hilum the the testicle (mediastinum testis) the carries sperm indigenous the seminiferous tubules to the efferent ducts.

Seminiferous tubules, situated in the testes, space where meiosis occurs and also the gametes (spermatozoa) are created. The seminiferous tubules are developed from primitive sex cords from the gonadal ridge. The epithelium of the tubule consists of tall, columnar cells dubbed Sertoli cells. Between the Sertoli cells space spermatogenic cells, which differentiate through meiosis to end up being sperm cells. There are two types of seminiferous tubules: convoluted, situated toward the lateral side, and also straight, together the tubule comes medially to form ducts the will exit the testis.

Efferent Ducts

The efferent ducts connect the rete testis v the initial section of the epididymis. There space two straightforward types of efferent ductule structure.

Multiple entries into the epididymis: This kind is watched in most big mammals. In humans and other large mammals, there are roughly 15–20 efferent ducts i m sorry occupy nearly one-third of the head the the epididymis.Single entry: This type is watched in most tiny animals such together rodents. This is identified by three to six ductules the merge right into a solitary small ductule prior to entering the epididymis.

The ductuli room unilaminar and also composed of columnar ciliated and also nonciliated (absorptive) cells. The ciliated cells stir the luminal fluids, which may assist ensure homogeneous absorb of water indigenous the fluid created by the testis. This outcomes in an increase in the concentration of luminal sperm. The epithelium is surrounded by a band of smooth muscle that helps come propel the sperm towards the epididymis.

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

The smooth muscle layer of the vas deferens contracts in waves of peristalsis during ejaculation. 2 ducts connect the left and also right epididymis come the ejaculatory ducts in stimulate to move sperm. In humans, each tube is about 30 centimeters (a foot) long,3 to 5 mm in diameter, and surrounded by smooth muscle. The sperm room transferred indigenous the vas deferens right into the urethra, collecting secretions indigenous the male accessory sex glands such as the seminal vesicles, prostate gland, and bulbourethral glands, which provide the mass of semen.

The procedure that deferentectomy, likewise known together a vasectomy, is a method of contraception in which the vas deferens room permanently cut, despite in some cases it have the right to be reversed. A contemporary procedure that does not encompass cutting the ducts entails injecting an obstructive material into the ductus come block the flow of sperm. Study in male contraception has concentrated primarily on the vas deferens v the usage of the intra-vas an equipment and reversible inhibition that sperm under guidance.

Accessory Sex Glands

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

Learning Objectives

Describe the attributes of masculine accessory sex glands

Key Takeaways

Key PointsSeminal glands contain seminal vesicles that develop 50–70% that the seminal fluid.The excretory duct that 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, maybe to block the progression of sperm from various other males.The prostate secretes 20–30% that the seminal fluid which dead the sperm in the ejaculate.The prostate surrounds the urethra listed below the bladder and can be felt in a rectal exam.Bulbourethral glands produce a pre-ejaculate cheap which lubricates and flushes out the urethra in preparation for the sperm.Key Termsbulbourethral gland: one exocrine gland i beg your pardon secretes a clear fluid upon sex-related arousal together pre-ejaculate (or Cowper’s fluid).Lipofuscin: Yellow-brown pigment granules created of lipid-containing residues of lysosomal digestion.prostate: A link tubuloalveolar exocrine gland the the masculine reproductive device in most mammals.seminal gland: A pair of basic tubular glands situated within the pelvisthat secrete fluid that partly composes semen.

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

See more: Inscribed ( 90 Foot Stone Oak Island Mystery, Oak Island Money Pit

Seminal Gland Anatomy

Each seminal gland develops as one outward expansion of the wall surface of ampulla of each vas deferens. They room curled and folded within the gland and can spread out to around 5 cm, yet the unfolded length is roughly 10 cm. The excretory duct that the seminal gland opens right into the vas deferens as it enters the prostate gland.

Seminal Gland Physiology and also Function

The seminal motor secrete a far-reaching proportion the the fluid that at some point becomes semen. Lipofuscin granules indigenous dead epithelial cells offer the secretion its yellowish color. About 50–70% the seminal fluid in human beings originates native the seminal vesicles, but is not expelled in the first ejaculate fractions which are overcame by spermatozoa and also zinc-rich prostatic fluid. Seminal vesicle fluid is alkaline, result in human being semen with a mildly alkaline pH. This help neutralize the acidity of the vaginal tract, expanding the expectancy of sperm. Acidic ejaculate (pH