REPRODUCTIVE SYSTEM
•The
reproductive organs of both genders are said to be in “slumber” until puberty
sets in.
Developmental Aspects
of the Reproductive System
•The sex of an individual is
already determined at the time of fertilization as:
FEMALE – XX
chromosome combination on the 23rd pair
(SEX CHROMOSOMES)
MALE – XY
chromosome combination
•The GONADS
(Primary Sex Organ) do not begin to form until about the 8th week of embryonic development
TESTES – Male Gonads
OVARY – Female Gonads
•Prior
to this time, the embryonic reproductive structures of males & females are
IDENTICAL, and are said to be in the INDIFFERENT STAGE.
•After
the gonads have formed, development of the accessory organs & external
genitalia begins.
•Whether
male or female structures will form depends entirely on whether TESTOSTERONE is present or absent.
•The
usual case is that, once formed, the embryonic testes produce testosterone and
the development of the male duct system & external genitalia follows.
•When
testosterone is NOT produced as in the case of the female embryos that form
ovaries, the female ducts and external genitalia results.
•Any
interference with the normal pattern of sex hormone production in the embryo
results in a bizarre abnormalities.
•If
the embryonic testes fail to produce testosterone, a genetic male develops the
female accessory structures and external genitalia.
•PSEUDOHERMAPHRODITES / mismatched - if a genetic
female is exposed to testosterone (if the mother has androgen-producing tumor
of her adrenal gland) the embryo has ovaries but develops male accessory ducts
and glands.
•TRUE HERMAPHRODITES – rare individuals who possess
both ovarian and testicular tissues.
•ABDOMINAL CAVITY – where male testes develops;
approximately the same location of the female ovaries.
•The
male testes descend to enter the scrotum
about 1 month before birth.
•CRYPTORCHIOISM - condition where testes fails to
descend
- sterility might happen if not operated
MALE REPRODUCTIVE
SYSTEM
•
Manufacture
male gametes (sperm) and deliver them to the woman’s reproductive tract.
Path of Testicles
Abdominal Cavity
Inguinal Canal
Scrotum
Divisions of the Male
Reproductive System
MALE
GONADS / TESTES
|
•Primary
sex organ of the male
•Exocrine
Function: sperm-producing
•Endocrine
Function: testosterone-producing
•Approx.
4 cm. long x 2.5 cm wide
•TUNICA ALBUGINEA – fibrous connective tissue capsule
which surrounds each testis and divides it into 2 tiny lobules
1 lobule = 1 – 4 tightly
coiled Seminiferous Tubules
•SEMINIFEROUS TUBULES – where sperm cells are
actually produced
•RETE TESTIS – network of tubules located on the side
of the testis carrying sperm from the seminiferous tubules to the epididymis
•INTERSTITIAL CELLS OF LEYDIG – lying in the soft
tissue surrounding the Seminiferous tubules
- produces testosterone
|
||
DUCT
SYSTEM (Transports System)
|
EPIDIDYMIS
|
•Provides
temporary storage site for immature sperm
cells from the seminiferous tubules & rete testis
•While
the young sperm cells make their way along the epididymis (20 days), they
mature, gaining the ability to swim
•When
a male is sexually stimulated, the wall of the epididymis contract to expel
the sperm to the vas deferens
|
|
DUCTUS
/ VAS DEFERENS
|
•Propels live sperm from the epididymis into the
urethra
•Ejaculation – “to
shoot forth”
•At
the moment of ejaculation, the walls create peristaltic waves that squeeze
the sperms forward
|
||
EJACULATORY
DUCT
|
•Passes
through the prostate gland to merge with the urethra
|
||
URETHRA
|
•Extends
from the bladder to the tip of the penis
•Carries
both urine & semen, however, they never
pass the urethra at the same time
•When
ejaculation happens, sperm enters the prostatic urethra from the ejaculatory
ducts, the urinary bladder spinchter contracts (shuts off)
•This
event not only prevents the passage of urine into the urethra, but also
prevents sperm from entering the urinary bladder
|
||
Prostatic
|
•surrounded
by the prostate gland
|
||
Membranous
|
•spanning
the distance from the prostatic urethra to the penis
|
||
Spongy
/ Penile
|
•runs
through the length of the penis
|
||
ACCESSORY
REPRODUCTIVE GLANDS / ORGANS
|
SEMINAL
VESICLE
|
•Located
at the base of a urinary bladder
•Contributes
60% of the fluid volume
•Thick,
yellowish secretion
•Nutrients
that activates the sperm cell:
sugar (fructose)
Vit. C
Prostaglandin
•The
duct of the seminal vesicle joins the vas deferens on the same side to form
EJACULATORY DUCT
|
|
PROSTATE
GLAND
|
•A
single gland about the size of a chestnut
•It
encircles the upper part of the prostatic urethra
just below the J. bladder
•The
secretion is a milky fluid that plays a role in activating sperm
•It
is located immediately anterior to the rectum, its size & texture can be
palpated by digital examination through the anterior rectal wall
|
||
COWPER’S
/ BULBOURETHRAL GLAND
|
•Tiny,
pea-sized gland inferior to the prostates
•Produce
a thick, clear mucus, that strains into the penile urethra
•This
secretion is the first to pass down the male urethra when a man becomes
sexually excited
•It
cleanses the urethra of traces of acidic urine
•Serves
a lubricant during copulation
|
||
EXTERNAL
GENITALS
|
SCROTUM
|
•”pouch”
•Divided
sac of skin that hangs outside the abdominal
cavity
•Between the legs and at the root of the penis
•Provides
the testes a temperature which is below body temperature because viable sperm
cannot be produced at normal body temperature
•Provides
a temperature 3˚ lower than the normal body
temperature specified to produce healthy sperm
|
|
PENIS
|
•Designed
to deliver sperm into the female birth canal
PARTS:
1.
Shaft –
skin-covered part which ends in an enlarged tip
2.
Glans penis –
represents the enlarged tip
3.
Prepuce / Foreskin – a cuff of
skin that folds downward because the skin covering the penis is loose
-
removed in circumcision
4.
Muscles that forms
the penis:
- Corpus cavernosa
penis
- Corpus
spongiosum penis
|
SEMEN
•Relative
alkalinity is pH 7.2-7.6 that help neutralize the acid environment of the female
vagina which is pH 3.5-4.0
•The basicity
protects the delicate sperm which become sluggish under acidic conditions
•Contains SEMINALPLASMIN
– antibiotic chemical that prevents bacterial multiplication
•Contain RELAXIN – enhance
sperm motility
•Milky white, sticky mixture of
sperm and accessory gland secretions
•Accessory Gland secretions
provide the medium and nutrients
•The fructose in the seminal vesicle provides essentially the energy fuel
of the sperms
•The amount of semen propelled
per ejaculation is relatively small, only 2 – 5 mL or a about a
teaspoonful but there are 50 – 150 M/ mL
CAUSES OF MALE INFERTILITY:
1.
Obstructions in the duct system
2.
Hormonal imbalances
3.
Excessive alcohol
FACTORS ANALYZED in SEMEN
ANALYSIS:
1.
Sperm count (lower than 20M/mL makes
pregnancy improbable)
2.
Motility and morphology (shape and
maturity)
3.
Semen volume
4.
pH
5.
Fructose content
What is the
influence of FSH(Follicle-stimulating hormone) and LH(Luteinizing hormone) of
the anterior lobe of the Pituitary Gland to male reproduction?
The hypothalamus secretes gonadotropin-releasing
hormone (GnRH), which enters the blood vessels leading to the anterior
pituitary gland. In response, the anterior pituitary gland secretes the gonadotropins called
luteinizing hormone (LH) and follicle-stimulating
hormone (FSH). LH, which in males has been referred to as interstitial cell-stimulating hormone (ICSH),
promotes development of the interstitial cells of the testes, and they, in
turn, secrete male sex hormones. FSH stimulates
the sustentacular cells of the seminiferous
tubules to proliferate, grow, mature, and respond to the effects of the male
sex hormone testosterone. Then, in the presence of FSH and testosterone, these
cells stimulate the spermatogenic cells to undergo
spermatogenesis, giving rise to sperm cells. The sustentacular cells
also secrete a hormone called inhibin,
which inhibits the anterior pituitary gland by negative feedback and thus prevents oversecretion of FSH.