Male Reproductive System Flashcards
Genitalia
- 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
Scrotum
- 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
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
varicocele
(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
spermatogenisis
(seminiferous tubules and spermatogenesis)
- the process of sperm formation
- begins at puberty
- an adult will form 400 million sperm/day

spermatogonia
- 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
-
primary and secondary **
3 stages of spermatogenisis
- Formation of Spermatocytes
- Meiosis
- Spermiogenisis
Stage 1: Formation of spermatocytes
(Spermatogenisis)
- 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
(Spermatogenesis)
- “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
(Spermatogenesis)
- 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

spermatozoon
- “animal seed”
- new sperm cell
- has head, tail and midpiece
Head of spermatozoon
- flat, sunflower seed-shaped nuclueus which contains:
- condensed chromatin
- helmetlike *acrosome *
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
- follicle-stimulating hormone (FSH)
- from anterior part of pituitart gland
- 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:
- basal compartment
- 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
- they’d activate the immune system
- must pass through adluminal compartment
Ways sustentacular cells assist sperm production
- convey nutrients to spermatogenic cells
- move these cells toward the tubule lumen
- phagocytize the cytoplasm that is shed as spermatids become sperm
- secrete *testicular fluid *
- secrete *adrogen-binding protein *
- 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
inhibin
- 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)
androgens
- 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
LH
- 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
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
vasectomy
- =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
Urethra
- in males, carries sperm from the ejactulatory ducts to the outside of body
- three parts:
- prostatic urethra in prostate
- membranous urethra in the urogenital diaphragm
- spongy urethra in the penis
seminal vesicles
aka
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:
- Fructose and other nutrients that nourish sperm
- *prostaglandins: *stimulates contraction of the uterus to help move sperm through female reproductive tract
- substances that suppress the immune response against semen in females
- subtances that enhance sperm motility
- enzymes that clot the ejaculated semen in the vagina and liquify it so sperm can swim out
- yellow pigment that shines under uv light
prostate
- 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
BPH
- 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
- questions about urine
- weak stream, hesitates to urine, strains to urine, feels bladded doesnt completely empty, must urinate at night, increased and urgent urining
- determine whether prostate is enlarged with digital rectal exam
- finger inserted into anal canal can feel prostate
- 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
prostatitis
- 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
penis
- “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)

circumcision
- 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
- corpus spongiosum
- & 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
- erection of penis
- allows it to penetrate vagina
- ejaculation
- expels semen into vagina
erection
- 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
ejaculation
- 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.
cloaca
(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
hypospadias
(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
gubernaculum
- the main theory for the descent of testis
- fibrous cord that extends caudally from the testis to floor of scrotal sac
- known to shorten
cryptorchidism
- 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
puberty
- 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
menopause
- 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
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Development of the internal reproductive organs in both sexes
important
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pg 744
