Anatomy of the Male Reproductive System Flashcards
the genetic sex of an individual is determined at the time of
fertilization by the sex chromosome that is carried by the sperm
there is no morphological indication of sex until
week six or seven of embryonic development
embyro can be described as
sexually bipotential or potentially bisexual
the gonads develop from
embryonic tissue called mesoderm
each gonad is
enclosed by germinal epithelium which surrounds large outer cortex and smaller central medulla
approximately 43 days after fertilization,
Y chromosome begins to affect indifferent gonads
Y chromosome carries a
sex-determining gene that produces testis-determining factor (TDF)
TDF directs
development of indifferent gonads into testes
two pairs of genital ducts are present during
the indifferent stage
mesonephros consists of
mesonephric tubules and mesonephric ducts
production of testosterone causes
mesonephros to differentiate into male reproductive ducts
paramesonephros consists of
a pair of Muellerian ducts
presence of Muellerian-inhibiting factor causes
paramesonephros to degenerate in males
the scrotum hangs from
the lower abdomen behind the base of the penis
scrotum consists of
loose skin, superficial fascia, and muscle tissue located just beneath skin
dartos is
a sheath of smooth muscle fibers
cremaster muscles are
thin strands of skeletal muscle that suspends testes
walls of scrotum contain
numerous sweat glands
a medial septum divides
the scrotum into two compartments, each containing one testis
location of septum can
be seen externally as median raphe
the location of the scrotum outside of the body cavity permits
thermoregulation of the testes to enhance the production and survival of sperm
dartos and cremaster muscles will contract in response to
cold temperatures
-draws testes closer to body to raise temp
dartos and cremaster muscles will relax in response to
warm temperatures
-this moves testes farther away from body to lower their temperature
blood vessels that suppply testes with blood form
pampiniform plexus
pampiniform plexus acts as a
conutercurrent heat exchanger to keep scrotal temp at 35 C
ideal temp
35 C
the testes are the
male gonads
testes are
cytogenic because they produce sperm cells
testes function as
endocrine glands because they produce testosterone
there are two oval testes and each is about
4cm long and 2.5 cm in diameter with a mass of about 15 grams
each testis is covered by
a pair of membranes
tunica vaginalis
lines scrotum
tunica albuginea divides
its testis into 200 to 300 lobules
each lobule contains
several highly coiled seminiferous tubules
each seminiferous tubues is approx
80 cm long
walls of seminiferous tubules contain
Sertoli cells
Sertoli cells protect and nourish
developing sperm cells
Sertoli cells can destroy
defective or damaged sperm cells
Sertoli cells form a
blood-testis barrier
blood testis barrier prevents
sperm from entering blood stream where their membrane antigens could trigger immune response
interstitial cells (of Leydig)
fill the spaces between the seminiferous tubules
interstitial cells of Leydig produce and secrete
testosterone
primary sex cords
finger like strands of germinal epithelium , grow into an indifferent gonad and carry primordial germ cells inward
medulla expands and forms
bulk of testis, while cortex condenses and forms tunica albyginea that surrounds testis
primary sex cords lose contact with
germinal epithelium as it starts to disapper
primary sex cords then become hollow and
start to form seminiferous tubules
cells that remain in walls of seminiferous tubules become
Sertoli cells
primordial germ cells within primary sex cords become
spermatogonia
cells in medulla become
interstitial cells of Leydig
the testes will descend through an
opening in the inguinal canal into the scrotum sometime during the seventh month of fetal development
failure of testes to descend is
cryptorchidism
undescended testes can cause
sterility because high temp in pelvic cavity can disrupt sperm production and maturation
risk for testicular cancer is
30 to 50 x greater for boys with cryptorchidism
testes will descend spontaneously during
first year in about 80% of cases of cryptorchidism
immature sperm will move from the seminiferous tubules into the
rete testies
rete tesits is
a network of about 100 short tubes that drain the seminiferous tubules
immature sperm will move from the rete testis into
a collection of short efferent ductules
the efferent ductules converge to form
a highly coiled, comma shaped epididymis along the superion/dorsal margin of the testis
immature sperm cells mature and become
motile over a period of 10 to 14 days as they pass through epididymis
sperm may be sotred in epididymis for
a month
mature sperm will move from the epididymis into the
ductus (vas) deferens
vas deferens joins together with
blood vessels, lymphatic vessels, nerves, and cremaster muscle to from spermatic cord, which passes through inguinal canal into pelvic cavity
behind urinary bladder, distal end of the vas deferens forms
enlarged ampulla for temporary sperm storage
the ampulla of the ductus (vas) deferens merges with a
duct from the seminal vesicle to form an ejaculatory duct behind the urinary bladder
ejaculatory duct transports
sperm into urethra
the urethra is 15 to 20 cm long and serves as
a common passage for sperm and urine
prostatic urethra extends from
urinary bladder through prostate gland
membranous urethra passes through
urogenital diaphragm in floor of pelvic cavity
spongy urethra passes through
spongy tissue of penis
a genital tubercle appears early during
embryonic development
urethral groove is a
shallow depression along midline of ventral surface of genital tubercle
walls of tissue on either side of urethral groove form
urethral folds
labiosacral swellings begin to develop
lateral to urethral folds
glans develops at the
end of the genital tubercle, which starts to form phallus
lateral buttresses form
on either side of phallus
testosterone triggers the genital tubercle to
differentiate by the 10th week following fertilization and the external genital start to appear distinctly male
the urethral folds fuse on
the ventral surface of the phallus to form a hollow tube that will eventually become the penile urethra
the lateral buttresses fold over to form
most of the shaft of the penis, and the glans penis expands from the glans at the end of the phallus
prepuce (foreskin)
will grow over glans penis but it will not retract until birth
the labiosacral swellings will fuse
and form the scrotum
The urethral groove elongates in
both directions
urethral groove elongates, on one end
breaks through the glans to form the external urethral orifice and the opposite end grows inward to form the bladder
one pair of outgrowths off urethral groove fuse to become
prostate gland
another pair of outgrowths will become
bulbourethral glands
the accessory glands produce and secrete
the liquid portion of semen
semen
a mixture of sperm, nutrient-rich mucus, proteins, and enzymes
seminal vesicles
pouchlike sacs at the base of the bladder that contribute about 60% of the volume of semen
fructose
energy source for sperm
proseminogelin
a protein that gets converted into seminogelin which causes semen to form temporary clot in vagina
prostaglandins
may cause mucus in cervical canal to become thinner, making it easier for sperm to travel from vagina into uterus- may stimulate contractions of smooth muscle in uterus and uterine tubes to assist sperm travel
prostate gland
a doughtnut shaped gland that surrounds the urethra as it exits the bladder- contributes to volume of semen
citric acid
used by sperm as a source of energy
acid phosphatase
a coaggulating agent that helps semen form clot in vagina
bicarbonate buffers
neutralize natural acidity in vagina
fibronolysin
decoaggulates a semen clot after vaginal acidity has been neutralized
serine protease
prostate specific antigen- an enzyme that breaks down proteins
bulbourethral glands
small spherical structures located etween the prostate gland on either side of the membranous urethra
bulbourethral glands secrete
alkaline substances to neutralize acidic residue left by urine in urethra
bulbourethral glands also secrete
mucus to lubricate penis for insertion into vagina
the penis
the male copulatory organ
root of penis
lies inside the body beneath the pubic bone and is attached to the urogenital diaphragm by skeletal muscles
shaft of penis
contains 3 cylindrical masses of erectile tissue each of which is surrounded by fibrous tissue
corpora cavernosa penis
dorsolateral masses and each contains an artery that dilates to produce erections
corpus spongiosum penis
a ventral mass that contains spongy urethra
glans penis
the enlarged distal end of penis
glans penis is richly innervated
with sensory nerve endings and external orifice
glans penis covering
covered with a loose skin fold called prepuce (foreskin)
small glands
beneath the foreskin, secrete waxy smegma
circumcision
surgical removal of all or part of prepuce
