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Flashcards in Male Reproductive System Deck (100):


  • Sex organs
  • divided into:
    • primary sex organs
    • accessory sex organs


Primary Sex Organs

  • AKA Gonads
  • "seeds"
  • Produce gametes (sex cells)
  • Produce sex hormones, functioning as endocrine glands
  • testes in males: produce sperm 
  • ovaries in females: produce ovum (egg)


accessory sex organs

  • all other genitalia in both sexes
  • includes:
    • internal glands and ducts
    • external genitalia



  • Pouch
  • a sac of skin and superficial fascia 
  • hangs inferiorly external of the abdominopelvic cavity at the root of the penis
  • contains testes/testicles
  • septum at the midline dividest scrotum into to compartments


Dartos Muscle

  • a layer of smooth muscle in the superficial fascia
  • responsible for wrinkling the scrotal skin (in cold conditions)
    • increases thickness 
    • reduces heat loss 


cremaster muscles

  • bands of skeletal muscle that extend inferiorly from the internal oblique muscles of the trunk
  • responsible for elevating the testes
  • relax in hot conditions


width and length of testes

  • average 2.5 cm (1 inch) in width
  • average 4 cm in height


Tunica Vaginalis

(Anatomy of Teste)

  • a serous sac inside the scrotum
  • each teste is posterior to and partially enclosed by this
  • develops as an out pocketing of abdominal peritoneal cavity
  • Consists of:
    • superficial parietal layer
    • intermediate cavity containing serous fluid
    • visceral layer that hugs the surface of the testes
  • Keep testes retroperitoneal


tunica albuginea

(Anatomy of Teste)

  • Just deep to the visceral layer of the tinica vaginalis
  • "white coat"
  • fibrous capsule of the testes
  • septal extensions project inward to divide the testes into 250-300 wedge-shaped compartments called lobules



(Anatomy of Teste)

  • 250-300 wedge shaped compartments in the testes
  • each contain 1-4 seminiferous tubules


seminiferous tubules

(Anatomy of Teste)

  • 1-4 coiled tubules in each lobule
  • the actual sperm factories
  • most are looped like hairpins


straight tubule

(Anatomy of Teste)

  • convergence of seminiferous tubules of each lobule, posteriorly
  • conveys sperm into rete testes


rete testes

(Anatomy of Teste)

  • "network of testes"
  • lined by simple cuboidal epithelium
  • a complex network of tiny branching tubes.
  • lies in the mediastinum testis
    • region of dense connective tissue
    • posterior part of testes
  • sperm leave here through efferent ductules


pampiniform plexus

(Anatomy of Teste)

  • venous network in the scrotum
  • from which testicular veins arise
  • "tendril shaped"
  • surround testicular arteries like climbing vines
  • absorb heat from arterial blood
    • cooling it before it enters the testes
    • keeping testes cool
    • called countercurrent heat exchange


innervation of testes

(Anatomy of Teste)


  • innervated by both divisions of the autonomic nervous system
  • abundant visceral sensory nerves transmit impulses
    • results in agonizing pain and nausea when testes are hit forcefully



(Anatomy of Teste)

  • a varicose vein in the pampiniform plexus
  • disrupts venous return from the testicles
  • found in 15% of men in gen pop
  • found in 40% of men being evaluated for fertility treatments
  • may cause sperm abnormalites




(seminiferous tubules and spermatogenesis)

  • the process of sperm formation
  • begins at puberty
  • an adult will form 400 million sperm/day



  • the stem cells from which sperm cells are formed
  • "sperm seed"
  • lie peripherally on the epithelial basal lamina
  • produce:
    • primary and secondary 
      • spermatocytes
      • spermatids
      • spermatozoa


3 stages of spermatogenisis

  1. Formation of Spermatocytes
  2. Meiosis
  3. Spermiogenisis


Stage 1: Formation of spermatocytes


  • Spermatogenia divide by mitosis
  • each division produces two daughter cells
    • Type A: remain at basal lamina to maintain germ cell line 
    • Type B: move toward lumen to become primary spermatocytes


Stage 2: Meiosis


  • "a lessening"
  • cell division that reduces the number of chromosomes found in typical body cells
  • essential part of gamete formation in both sexes
  • Meiosis I:
    • primary spermatocytes produce 2 secondary spermatocytes
  • Meiosis II
    • secondary spermatocyte produce 2 small cells called spermatids


Stage 3: Spermiogenesis


  • spermatids differentiate into sperm (Spermatozoon)
    • fashions tail, sheds cytoplasm
  • sperm detaches from seminiferous tubule and enters lumen
  • do not gain ability to swim until after they leave testes




  • "animal seed"
  • new sperm cell
  • has head, tail and midpiece


Head of spermatozoon


  • flat, sunflower seed-shaped nuclueus which contains:
    • condensed chromatin
    • helmetlike acrosome 




Head of spermatozoon

  • "tip piece" 
  • a lysosome-like vesicle made by the Golgi apparatus
  • contains digestive enzymes that enable sperm to penetrate an egg


midpiece of spermatozoon

  • thickened first part of tail
  • contains mitochondria spiraled tightly around the core of the tail
    • provide whiplike movements of the tail that propel the sperm through the reproductive tract of the female


tail of spermatozoon

  • long, elaborate flagellum 
  • motile cytoskeleton has grown out from a centiole near nucleus


Hormones that control spermatogenesis

  1. follicle-stimulating hormone (FSH)
    • from anterior part of pituitart gland
  2. testosterone
    • primary male sex hormone produced by testes


Sustentacular Cells


(seminiferous tubules and spermatogenesis)

  • surround spermatogenic cells
  • AKA sertoli cells
  • extend from the basal lamina to the lumen of the seminiferous tubule
  • bound to each other by tight junctions on lateral membranes
  • divide the seminiferous tubule into two compartments:
    1. basal compartment
    2. adluminal compartment


basal compartment

of seminiferous tubule


  • extends from the basal lamina to the tight junctions of sustentacular cells
  • contains spermatogonia and earliest spermatocytes


Adluminal Compartment

of the seminiferous tubule

  • "near the lumen"
  • lies internal to the tight junctions of sustentacular cells
  • includes more advanced spermatogenic cells and the lumen of the tubule


Blood-testis barrier

  • tight junctions of the sustentacular cells
  • prevents the escape of membrane antigens of differentiating sperm through the basal lamina and into the bloodstream
    • they'd activate the immune system
      • immune system's response would destroy gametes and produce sterility
  • must pass through adluminal compartment


Ways sustentacular cells assist sperm production

  1. convey nutrients to spermatogenic cells
  2. move these cells toward the tubule lumen
  3. phagocytize the cytoplasm that is shed as spermatids become sperm
  4. secrete testicular fluid 
  5. secrete adrogen-binding protein 
  6. secrete inhibin


testicular fluid


  • secreted from sustentacular cells
  • secreted into the tubule lumen
  • pressure of fluid pushes sperm through tubule and out of testes


androgen-binding protein

  • secreted from sustentacular cells

  • concentrates male sex hormone (testosterone) near the spermatogenic cells

  • testosterone stimulates the spermatogenesis



  • hormone secreted by sustentacular cells
  • slows the rate of sperm production (when necessary) 
    • inhibits FSH secretion from pituitary gland


Myoid Cells


(seminiferous tubules and spermatogenesis)

  • smooth-muscle-like cells
  • surround the seminiferous tubules in several layers
  • contract rhythmically
  • may help squeeze  sperm and testicular fluid through the tubules and out of the testis


interstitial cells


(seminiferous tubules and spermatogenesis)

  • leydig cells
  • spherical/polygon-shaped cells
  • found in clusters in the loose connective tissue between seminiferous tubules
  • make and secrete androgens (male sex hormone--testosterone being the main one)



  • male sex hormone
  • made and secreted by interstitial(leydig) cells
  • Main type: Testosterone
  • circulates through the body and maintains all male sex characteristics and sex organs
  • all male genitalia atrophy if testes (and testosterone) are removed


Luteinizing Hormone 



  • a hormone from the anterior part of the pituitary gland
  • controlls secretion of testosterone by interstitial cells



efferent ductules

  • lined by simple columnar epithelium
  • where sperm leaves testis 
  • ciliated epithelia and smooth muscle help sperm move along
  • nonciliated epithelia absorbs most testicular fluid
  • from here sperm enters duct of the epididymis



  • "beside the testis"
  • where sperm mature
  • comma-shaped organ
  • arches over the posterior and lateral side of the testis
  • contains:
    • head
    • duct of epididymis
      • body
      • tail


head of epididymis

  • contains the efferent ductules
  • empties into duct of epididymis


duct of epididymis

  • a highly coiled duct
  • completes the head 
  • forms all of the body and tail
  • uncoiled length of over 6m (20 feet)
    • longer than entire intestine


histology of the duct of epididymis

  • tall pseudostratified columnar epithelium
  • luminal surface has long stereocilia
    • not cilia
    • do not move
  • allow more reabsorption of testicular fluid to take place
  • transfer nutrients and secretions to sperm in the lumen of the epididymis
  • external to the epithelium lies a layer of smooth muscle


maturity of a sperm

  • leave testis immotile
  • 20 day journey through duct of epididymis
    • sperm learn to swim
    • gain ability to ferilize egg through acrosome reaction
  • sperm are ejaculated from epididymis, not testis


ductus deferens

  • "carrying away"
  • aka vas deferens
  • stores and transports sperm during ejaculation
  • 45 cm (18 inches) long
  • Runs:
    • from tail of epididymis
    • superiorly within the spermatic cord
    • goes through inguinal canal
    • pierces anterior abdominal wall
    • enters pelvic cavity
    • runs posteriorly along the lateral wall of true pelvis
    • arches medially over the ureter
    • descends along posterior wall of bladder
    • expands as the ampulla of the ductus deferens
    • joins with duct of seminal vessicle
    • forms short ejaculatory duct
    • runs within prostate
    • empties into the prostatic urethra


ampulla of the ductus deferens

  • "flask"
  • distal end of ductus deferens
  • expands
  • joins with the duct of the seminal vesicle to form the short ejaculatory tract


ejaculatory duct

  • runs within prostate
  • empties into the prostatic urethra


histology of ductus deferens

  • inner mucosa
    • pseudostratified epithelium (same as epididymis)
    • lamina propria
  • exteremely thick muscularis
    • creates strong peristaltic waves that rapidly propel sperm through ductus deferens into urethra
  • outer adventitia



  • =cutting the vas
  • tie or cut ductus deferens 
  • sperm is produced but is phagocytized in epididymis
  • can now be reveresed at over 50% success rate


spermatic cord

  • a tube a fascia that contains:
    • testicular vessels
    • testicular nerves
    • ductus deferens


inguinal canal

  • an obliquely oriented trough in anterior abdominal wall
  • partially formed by inguinal ligament


superficial inguinal ring

  • medial opening of the inguinal canal 
  • v shaped opening in this aponeurosis
  • runs laterally to the deep inguinal ring


deep inguinal ring

  • an opening in the fascia deep to the abdominal muscle transversus abdominus
  • where the ductus deferens and testicular vessels enter the pelvic cavity


inguinal hernia

  • deep inguinal ring and the fascia just medial to it are very weak areas of the abdominal wall
  • coils of intestine or omentum can be forced anteriorly through these areas
  • sometimes push all the way into the scrotum
  • heavy lifting/straining
  • can lead to fatal gangrene
  • can be surgically repaired
  • much less common in women



  • in males, carries sperm from the ejactulatory ducts to the outside of body
  • three parts:
    1. prostatic urethra in prostate
    2. membranous urethra in the urogenital diaphragm
    3. spongy urethra in the penis


seminal vesicles


seminal glands

  • posterior surface of bladder
  • shape/length of finger (5-7cm coiled)
  • true length=15cm
  • honeycomb of crypts and chambers


histology of seminal vesicles

  • secretory pseudostratified columnar epithelium
  • fibrous dense connective tissue
  • external layer of smooth muscle
    • contracts during ejaculation to empty the gland


secretion of seminal vesicles

  • constitute for 60% of volume of semen
  • viscous seminal fluid mix that contains:
  1. Fructose and other nutrients that nourish sperm
  2. prostaglandins: stimulates contraction of the uterus to help move sperm through female reproductive tract
  3. substances that suppress the immune response against semen in females
  4. subtances that enhance sperm motility
  5. enzymes that clot the ejaculated semen in the vagina and liquify it so sperm can swim out
  6. yellow pigment that shines under uv light



  • size and shape of chesnut
  • encircles first part of urethra inferior to bladder
  • consists of 20-30 compound tubuloalveolar glands of three classes


3 classes of tubuloalveolar glands


of the prostate

  • main
  • submucosal
  • mucosal

embedded in fibromuscular stroma


Fibromuscular Stroma

of prostate

  • mass of dense connective tissue and smooth muscle
  • contracts during ejaculation to squeeze the prostate secretion into urethra
  • compound tubuloalveolar glands embedded here


prostatic secretion

  • 33% volume of semen
  • milky fluid
  • various substances that enhance sperm motility and enzymes that clot and liquify ejaculated semen
  • postate-specific antigen (PSA)
    • enzyme that ​liquifies semen
    • measuring PSA levels in blood is important for prostate cancer screening


Benign Prostatic Hyperplasia


  • common non cancerous tumor
  • 50% of men at 50 and 80% of of men at 70
  • mucosal gland in prostate experiences uncontrolled growth
  • proliferation of stoma cells
  • urethra is constricted
  • micturition becomes difficult
  • leads to urinary retention, continual dribbling of urine, urinary tract infections, formation of kidney stones


diagnosing BPH

  1. questions about urine
    • weak stream, hesitates to urine, strains to urine, feels bladded doesnt completely empty, must urinate at night, increased and urgent urining
  2. determine whether prostate is enlarged with digital rectal exam
    • ​​finger inserted into anal canal can feel prostate
  3. potential blood test checking PSA


treatment of BPH

  • drugs that inhibit production of testosterone
    • tumor cells depend on it
  • drugs that relax prostate's smooth muscle
  • removal or destruction of prostate if necessary



  • inflammation of prostate
  • single most common reason that men consult urologist


bulbourethral glands

  • pea-sized glands
  • inferior to prostate
  • within urogenital diaphragm
  • produce mucus when a male becomes sexually excited prior to ejaculation
    • neutrolizes traces of acidic urine in urethra
    • lubricates the urethra for smooth passage of semen



  • "tail"
  • male organ of sexual intercourse
  • delivers sperm into female reproductive tract
  • penis + scrotum make up external genitalia 
  • Consists of:
    • root (attached)
    • shaft/body (free)
    • glans penis (enlarged tip)
    • prepuce (cuff/foreskin)



  • 60% of babies in USA
  • surgical removal of foreskin
  • controversial
    • opponents say its unnecessary and causes too much pain
    • proponents say it reduces risk of penile cancer and infections to the:
      • glans
      • urethral
      • urinary tract


Internal parts of penis

  • spongy urethra
  • 3 long cylindrical bodies (corpus)
    • corpus spongiosum
    • corpora cavernosa


erectile bodies

of penis


  • thick tube
  • covered by dense connective tissue
  • filled with a network of partitions made of smooth muscle and connective tissue
    • filled with vascular spaces
  1. corpus spongiosum
  2.  & 3. copora cavernosa


corpus spongiosum

(erectile body of penis)

  • midventral erectile body
  • surrounds spongy urethra
  • enlarges distally to form glans penis
  • proximally forms root bulb of the penis


bulb of the penis

(of the corps spongiosum erectile body of penis)

  • secured to the urogenital diaphragm
  • covered externally by a sheetlike bulbospongiosus muscle


corpora cavernosa

(erectile body of penis)

  • paired
  • dorsal erectile bodies
  • make up most of the mass of the penis
  • proximal ends in the root cura (2 crus) of the penis


crura of penis

  • 2 crus of the penis
  • anchored to the pubic arch of the bony pelvis
  • covered by ischiocavernosus muscle


phases of sexual response

  1. erection of penis
    • allows it to penetrate vagina
  2. ejaculation
    • expels semen into vagina




  • Deep artery allows infusion of blood into penis
  • engorgement of erectile bodies with blood
  • largely parasympathetic control
  • erectile bodies expand and blocks the vein that normally drains them
    • allowing engorgement to be maintained



  • under sympathetic control
  • begins with strong, sympathetically induced contraction of smooth muscle
  • semen is squeezed towards and into urethra


Male Perineum

  • "around the anus"
  • contains:
    • scrotum
    • root of penis
    • anus
  • diamond shaped area
  • between pubic symphysis anteriorly 
  • coccyx posteriorly
  • ischial tuberosities laterally


Gonadal Ridges

(embryonic development of sex organs)

  • masses of intermediate mesoderm
  • form bulges on the dorsal abdominal wall of the lumbar region
  • just medial to mesenphros (embryonic kidney)
  • early development of gonads at week 5


mesonephric (wolffian) ducts


(embryonic development of sex organs)

  • the future male ducts
  • develop to medial to the paramesonephric (mullerian) ducts [future female ducts]
  • empties into the cloaca
  • becomes the vas deferens in the male; it involutes in the female.


paramesonephric (mullerian) ducts


(embryonic development of sex organs)

  • future female ducts
  • develop laterally to the mesonephric (wolffian) ducts [future male ducts]
  • empty into the cloaca 
  • becomes the fallopian tubes in the female; it involutes or becomes useless in the male.




(embryonic development of sex organs)

  • future bladder and urethra
  • receives from mesonephric/paramesonephric ducts


sexually indifferent stage


(embryonic development of sex organs)

  • gonadal ridge and ducts are structurally identical in both sexes
  • week 5


metanephric duct

(embryonic development of sex organs)

  • It becomes the ureters in both male and female


genital tubercle


(Embryonic development of sex organs)

  • a small projection on external perineal surface
  • during sexually indifferent stage
  • on male/female
  • lies superficial to urogenital sinus of cloaca
  • forms most of the penis in males
  • becomes clitoris in females


urethral groove

(Embryonic development of sex organs)

  • during sexually indifferent stage
  • serves as external opening of the urogenital sinus
  • runs between the genital tubercle and the anus
  • flanked laterally by the urethral (genital) folds and the labioscrotal swellings
  • persists as vestibule in women


Urethral folds 

(Embryonic development of sex organs)

  • fuse at midline in males
  • form penile urethra in males
  • unfused in females
  • become the labia minora in females


labioscrotal swellings

(Embryonic development of sex organs)

  • during the sexually indifferent stage
  • fuse at midline to form scrotum in males
  • unfused, becomes labia majora in females



(Embryonic development of sex organs)

  • most common congenital abnormality of male urethra
  • 1% of male births
  • results from failure of two urethral folds to fuse completely
  • urethral openings on the undersurface of penis are produced
  • more urine exits from underside of penis than from tip
  • corrected surgically


congenital inguinal hernias

  • most common type of hernia
  • when vaginal processes do not close in boys
  • leaves open path to scrotum for hernia to occur



  • the main theory for the descent of testis
  • fibrous cord that extends caudally from the testis to floor of scrotal sac
  • known to shorten



  • congentital condition in newborns
  • when one or both testis fail to decend to scrotum
  • could be located in inguinal canal (typically) or pelvic cavity
  • teste is sterile due to higher temperatures
  • could lead to increased likelihood of testicular cancer



  • period of life when reproductive organs grow to full size
  • reproduction becomes possible
  • between 10 and 15
  • changes occur to rising levels of gonadal hormones
    • testosterone in males
    • estrogen in female



  • occurs in women 46-56
  • follicles in ovaries degenerate at staggering rate
  • ovulation and mentruation cease
  • no equivalent for men
  • hormones stop secreting
  • reproductive organs begin to atrophy and dry


Descent of the Testes




Development of the internal reproductive organs in both sexes



pg 744