Anatomy of the Male Reproductive System The primary sex organs are the testes The accessory organs include a complex set of ducts and tubules leading from the testes to the penis The penis is the organ of copulation ID: 397044
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Slide1
MALE REPRODUCTIVE SYSTEMSlide2
Anatomy of the Male
Reproductive System
The primary sex organs are the
testes.
The accessory organs include a complex set of ducts and tubules leading from the testes to the penis.
The penis is the organ of copulation.Slide3
Anatomy of the Male
Reproductive System
Figure 28.11Slide4
Scrotum
The
scrotum
is a skin-covered sac that provides the testes with a cooler environment than body temperature.Sperm develop successfully at approximately 3 Celsius below normal body temperature.
The scrotum is homologous to the labia majora in the female.A raphe separates the two scrotal sacs.The dartos muscle is a layer of smooth muscle that is part of the wall of the scrotum.Slide5
Scrotum
Figure 28.12Slide6
Spermatic Cord
The
spermatic cord
originates at the inguinal canal. It consists of the following: Testicular artery—
branch of the abdominal aorta Pampiniform plexus—a network of veins surrounding the testicular artery Cremaster muscle and fascia—formed from muscle fiber extensions of the internal oblique muscle Autonomic nerves— travel with plexus and connect to the testesSlide7
Spermatic Cord
Figure 28.12Slide8
Testes
The function of the testes is twofold:
production of sperm
production and secretion of androgens (male sex hormones), the most common being testosteroneEach testis is covered anteriorly and laterally by a serous membrane called the tunica vaginalis
The tunica vaginalis has an outer parietal layer and an inner visceral layerSlide9
Testes
Figure 28.13Slide10
Testes
Located just deep to the visceral layer and in contact with the testis is a thick, whitish fibrous capsule covering the testis called the
tunica albuginea.
The tunica albuginea projects into the interior of the testis as the mediastinum testis through which blood vessels, lymphatic vessels, and some nerves enter and leave the testis.Slide11
Testes
The tunica albuginea projects internally into the testes to form
septa.
The septa subdivide to form about 250 lobules.Each lobule contains four convoluted seminiferous tubules.Slide12
Seminiferous Tubules
Seminiferous tubules contain two types of cells:
1.
Sustentacular cells—nondividing support cells that assist with sperm development; connected to each other by tight junctions and form the blood-testis barrier
2. A population of dividing germ cells that continuously produce sperm beginning at puberty Slide13
Interstitial Space
Spaces external to and in between seminiferous tubules
Interstitial cells
reside in these space and produce hormones called androgens
Figure 28.13
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The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Spermatids
Sperm cells
Spermatogonia
Interstitial cells
LM 250x
(b) Seminiferous tubule, cross section
Seminiferous
tubule
Tubule lumen
Sustentacular
cells
b: © The McGraw-Hill Companies, Inc./Photo by Dr. Alvin TelserSlide14
Spermatogenesis and Spermiogenesis
Figure 28.14Slide15
Spermatogenesis and Spermiogenesis
Figure 28.14Slide16
Stages of SpermatogenesisSlide17
Ducts in the Male Reproductive System
Beginning at the testis and extending through the penis, the ducts are:
Rete testis
Efferent ductules Epididymis Ductus deferens
Ejaculatory duct UrethraSlide18
Ducts in the Male Reproductive System
Figure 28.15Slide19
Rete Testis
Receive sperm from seminiferous tubules
Figure 28.13Slide20
Efferent Ductules
Connect rete testis to epididymis
Figure 28.13Slide21
Epididymis
Situated on the posterosuperior surface of the testes, the
epididymis
has three regions: - head - body - tailInternally, the epididymis contains a long convoluted
duct of the epididymisThe epididymis stores sperm and serves in the maturation process of spermSlide22
Epididymis
Figure 28.13Slide23
Ductus Deferens
Sperm leaving the epididymis enter the
ductus deferens
(vas deferens).This tube travels within the spermatic cord and enters the pelvic cavity through the inguinal canal.As the ductus deferens approaches the prostate gland, it enlarges to form the ampulla.
The ampulla unites with the proximal portion of the seminal vesicle to form the ejaculatory duct.Slide24
Ductus Deferens
Figure 28.15Slide25
Ejaculatory Duct
Formed by a uniting of the ductus deferens and the seminal vesicle
Located within the substance of the prostate gland between 1–2 cm long and conducts sperm from the ductus deferens to the prostatic urethraSlide26
Ejaculatory Duct
Figure 28.15Slide27
Urethra
Transports semen from both ejaculatory ducts to the outside of the body
The male urethra is subdivided into three regions:
prostatic urethramembranous urethra
spongy urethraSlide28
Urethra
Figure 28.15Slide29
Accessory Glands
There are three glands that secrete fluids to mix with sperm to create
seminal fluid.
These secretions nourish the sperm and neutralize the acidity of the vagina.The three glands are as follows:
seminal vesiclesprostate glandbulbourethral glandsSlide30
Seminal Vesicles
The paired
seminal vesicles
are located on the posterior surface of the urinary bladder lateral to the ampulla of the ductus deferens.They secrete a viscous, whitish-yellow, alkaline fluid containing fructose and prostaglandins.Slide31
Seminal Vesicles
Figure 28.15Slide32
Seminal Vesicles
and Prostate Gland
Figure 28.16
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Seminal vesicle
LM 80x
LM 25x
(b) Prostate gland
Tubuloalveolar
glands in
prostate gland
Mucosal folds
in seminal
vesicle
(a) Seminal vesicle
Prostate
gland
a: © Carolina Biological/Visuals Unlimited; b: © The McGraw-Hill Companies, Inc./Photo by Dr. Alvin TelserSlide33
Prostate Gland
The
prostate gland
is located immediately inferior to the urinary bladder.It produces substances that are secreted directly into the prostatic urethra.
Prostatic secretion is slightly acidic and contains mucin, citric acid (nutrient for sperm), seminalplasmin (antibacterial),and prostatic-specific antigen (PSA, an enzyme that helps liquify semen).Slide34
Prostate Gland
Figure 28.15Slide35
Prostate Gland
Figure 28.11
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Urinary bladder
Pubic symphysis
Ductus deferens
Urethra
Urogenital diaphragm
Penis
Glans
Ureters
Ampulla of ductus deferens
Seminal vesicle
Ejaculatory duct
Prostate gland
Bulbourethral gland
Anus
Epididymis
Scrotum
TestisSlide36
Bulbourethral Glands
The
bulbourethral glands
are located in the urogenital diaphragm on either side of the membranous urethra.Mucin is secreted from these glands and enters the spongy urethra at the base of the penis.Slide37
Bulbourethral Glands
Figure 28.15Slide38
Semen
Seminal fluid from the three accessory glands combines with sperm from the testes to make up
semen.
When released during intercourse, semen is called ejaculate.Semen normally measures about 3–5 ml in volume and contains 200–500 million sperm.Slide39
Penis
The
penis
and the scrotum form the external genitalia in males.Internally, the attached portion of the penis is the root forming both the bulb
and the crura of the penis.The body (shaft) is the elongated portion of the penis.The tip of the penis is the glans, which surrounds the external urethral orifice.Slide40
Anatomy of the Penis
Figure 28.17Slide41
Penis
The shaft of the penis is comprised of three parallel, cylindrical erectile bodies:
Paired
corpora cavernosa are located dorsolaterally and terminate at the distal shaft of the penis
A single corpus spongiosum is inferior and midline and surrounds the spongy urethra The distal end of the corpus spongiosum continues within the glansSlide42
Anatomy of the Penis
Figure 28.17Slide43
Circumcision
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Prepuce
(b) Uncircumcised penis
(a) Circumcised penisSlide44
Erection and Ejaculation
The erectile bodies are composed of
venous spaces,
which fill with blood from a central artery to produce an erection.Parasympathetic in nervation is responsible for penile erection.Ejaculation is the expelling of semen from the penis, in part, by the rhythmic contraction of the smooth muscle of the urethra.
Sympathetic in nervation promotes ejaculation.Slide45
Development of the
Reproductive Systems
Figure 28.18
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Mesonephros
Genital ridge
Kidney
Mesonephric duct
Cloaca
Male
Female
Sexually Indifferent Stage
Testes
Efferent ductules
Epididymis
Urinary bladder
Seminal vesicle
Urinary bladder
Seminal vesicle
Prostate gland
Bulbourethral gland
Ductus deferens
Epididymis
Efferent ductules
Testis
Urethra
At birth
Ovaries
Ovary
Uterus
Vagina
Urethra
Hymen
At birth
Paramesonephric
duct
Weeks 5–6
Paramesonephric
duct forming the
uterine tube
Mesonephric
duct
(degenerating)
Paramesonephric
duct (degenerating)
Mesonephric duct
forming the ductus
deferens
Urogenital sinus
forming the urethra
Weeks 10–12
Weeks 10–12
Urogenital sinus forming
the urethra and inferior vagina
Fused paramesonephric
ducts forming the uterus
Uterine
tube
Urinary bladder
(moved aside)
Urinary bladder
(moved aside)Slide46
Development of the
Reproductive Systems
Figure 28.19