1. Male Reproductive System

2. Reproductive System Primary sex organs (gonads): testes and ovaries
Produce sex cells (gametes)
Secrete steroid sex hormones
Androgens (males)
Estrogens and progesterone (females)
Accessory reproductive organs: ducts, glands, and external genitalia

3. Reproductive System Sex hormones play roles in
Development and function of the reproductive organs
Sexual behavior and drives
Growth and development of many other organs and tissues

4. Male Reproductive System
Testes (within the scrotum) produce sperm
Sperm are delivered to the exterior through a system of ducts
Epididymis, ductus deferens, ejaculatory duct, and the urethra
Accessory sex glands: seminal vesicles, prostate, and bulbourethral glands
Empty secretions into the ducts during ejaculation

5. Ureter Urinary bladder Prostatic urethra Peritoneum Seminal vesicle
Membranous
urethra
Ampulla of
ductus
deferens
Urogenital
diaphragm
Pubis
Ejaculatory
duct
Corpus
cavernosum
Rectum
Corpus
spongiosum
Prostate
Bulbourethral
gland
Spongy urethra
Epididymis
Anus
Glans penis
Bulb of penis
Prepuce
Ductus (vas)
deferens
Testis
External
urethral orifice
Scrotum
Figure 27.1

6. The Scrotum Sac of skin and superficial fascia
Hangs outside the abdominopelvic cavity
Contains paired testes
3C lower than core body temperature (temperature necessary for sperm production)
Temperature is kept constant by two sets of muscles
Smooth muscle that wrinkles scrotal skin (dartos muscle)
Bands of skeletal muscle that elevate the testes (cremaster muscles)

7. Urinary bladder Superficial inguinal ring (end of inguinal canal)
Testicular artery
Spermatic cord
Ductus (vas)
deferens
Penis
Autonomic
nerve fibers
Middle septum
of scrotum
Pampiniform
venous plexus
Cremaster muscle
External spermatic
fascia
Epididymis
Tunica vaginalis
(from peritoneum)
Superficial fascia
containing dartos
muscle
Tunica albuginea
of testis
Scrotum
Internal spermatic
fascia
Skin
Figure 27.2

8. The Testes Surrounded by two tunics
Tunica vaginalis, derived from peritoneum
Tunica albuginea, the fibrous capsule
Divided into 250–300 lobules, each containing 1–4 seminiferous tubules (site of sperm production)
Sperm are conveyed through
Seminiferous tubules
Tubulus rectus
Rete testis
Efferent ductules
Epididymis
Blood supply comes from the testicular arteries and testicular veins
Spermatic cord encloses nerve fibers, blood vessels, and lymphatics that supply the testes
Interstitial (Leydig) cells outside the seminiferous tubules produce androgens  Testosterone

9. Spermatic cord Blood vessels and nerves Ductus (vas) deferens
Head of epididymis
Testis
Efferent ductule
Seminiferous
tubule
Rete testis
Lobule
Straight tubule
Septum
Tunica albuginea
Body of epididymis
Tunica vaginalis
Duct of epididymis
Cavity of
tunica vaginalis
Tail of epididymis
(a)
Figure 27.3a

10. The Penis External genitalia are the scrotum and the penis
Penis consists of
Root and shaft that ends in the glans penis
Prepuce, or foreskin—the cuff of loose skin covering the glans
Circumcision is the surgical removal of the foreskin
Crura: anchors penis to the pubic arch
Spongy urethra and three cylindrical bodies of erectile tissue (spongy network of connective tissue and smooth muscle with vascular spaces)
Corpus spongiosum surrounds the urethra and expands to form the glans and bulb
Corpora cavernosa are paired dorsal erectile bodies
Erection: erectile tissue fills with blood, causing the penis to enlarge and become rigid

11. Figure 27.4 Ureter Ampulla of ductus deferens Seminal vesicle
Urinary bladder
Ejaculatory duct
Prostate
Prostatic urethra
Orifices of prostatic ducts
Bulbourethral gland and duct
Membranous urethra
Urogenital diaphragm
Bulb of penis
Root of penis
Crus of penis
Bulbourethral duct opening
Ductus deferens
Corpora cavernosa
Epididymis
Corpus spongiosum
Shaft (body) of penis
Testis
Section of (b)
Spongy urethra
Glans penis
Prepuce (foreskin)
(a)
External urethral orifice
Dorsal vessels
and nerves
Corpora cavernosa
Urethra
Skin
Tunica albuginea of erectile bodies
Deep arteries
(b)
Corpus spongiosum
Figure 27.4

12. The Male Duct System Epididymis Ductus deferens Ejaculatory duct
Urethra

13. Epididymis Head: contains the efferent ductules Duct of the epididymis
Microvilli (stereocilia) absorb testicular fluid and pass nutrients to stored sperm
Nonmotile sperm enter, pass slowly through, and become motile
During ejaculation the epididymis contracts, expelling sperm into the ductus deferens

14. Ductus Deferens and Ejaculatory Duct
Ductus deferens / Vas deferens
Passes through the inguinal canal
Expands to form the ampulla and then joins the duct of the seminal vesicle to form the ejaculatory duct
Propels sperm from the epididymis to the urethra
Vasectomy: cutting and ligating the ductus deferens, which is a nearly 100% effective form of birth control

15. Urethra Conveys both urine and semen (at different times)
Has three regions
Prostatic urethra
Membranous urethra
Spongy (penile) urethra

16. Figure 27.4 Ureter Ampulla of ductus deferens Seminal vesicle
Urinary bladder
Ejaculatory duct
Prostate
Prostatic urethra
Orifices of prostatic ducts
Bulbourethral gland and duct
Membranous urethra
Urogenital diaphragm
Bulb of penis
Root of penis
Crus of penis
Bulbourethral duct opening
Ductus deferens
Corpora cavernosa
Epididymis
Corpus spongiosum
Shaft (body) of penis
Testis
Section of (b)
Spongy urethra
Glans penis
Prepuce (foreskin)
(a)
External urethral orifice
Dorsal vessels
and nerves
Corpora cavernosa
Urethra
Skin
Tunica albuginea of erectile bodies
Deep arteries
(b)
Corpus spongiosum
Figure 27.4

17. Accessory Glands: Seminal Vesicles
Produces viscous/thick alkaline seminal fluid
70% of the volume of semen
Duct of seminal vesicle joins the ductus deferens to form the ejaculatory duct

18. Accessory Glands: Prostate
Encircles part of the urethra inferior to the bladder
Secretes milky, slightly acid fluid:
Plays a role in the activation of sperm
Enters the prostatic urethra during ejaculation

19. Accessory Glands: Bulbourethral Glands (Cowper’s Glands)
Pea-sized glands inferior to the prostate
Prior to ejaculation, produce thick, clear mucus
Lubricates the glans penis
Neutralizes traces of acidic urine in the urethra

20. Figure 27.4 Ureter Ampulla of ductus deferens Seminal vesicle
Urinary bladder
Ejaculatory duct
Prostate
Prostatic urethra
Orifices of prostatic ducts
Bulbourethral gland and duct
Membranous urethra
Urogenital diaphragm
Bulb of penis
Root of penis
Crus of penis
Bulbourethral duct opening
Ductus deferens
Corpora cavernosa
Epididymis
Corpus spongiosum
Shaft (body) of penis
Testis
Section of (b)
Spongy urethra
Glans penis
Prepuce (foreskin)
(a)
External urethral orifice
Dorsal vessels
and nerves
Corpora cavernosa
Urethra
Skin
Tunica albuginea of erectile bodies
Deep arteries
(b)
Corpus spongiosum
Figure 27.4

21. Semen Mixture of sperm and accessory gland secretions
Contains nutrients (fructose), protects and activates sperm, and facilitates their movement (e.g., relaxin)
Prostaglandins in semen
Decrease the viscosity of mucus in the cervix
Stimulate reverse peristalsis in the uterus

22. Semen
Alkalinity neutralizes the acid in the male urethra and female vagina
Antibiotic chemicals destroy certain bacteria
Only 2–5 ml of semen are ejaculated, containing 20– 150 million sperm/ml

23. Male Sexual Response Erection
Enlargement and stiffening of the penis from engorgement of erectile tissue with blood
Initiated by sexual stimuli, including:
Touch, erotic sights, sounds, and smells
Can be induced or inhibited by emotions or higher mental activity
Parasympathetic reflex promotes release of nitric oxide (NO)
causes erectile tissue to fill with blood
Expansion of the corpora cavernosa
Compresses drainage veins and maintains engorgement
Corpus spongiosum keeps the urethra open
Impotence: the inability to attain erection

24. Male Sexual Response Ejaculation
Propulsion of semen from the male duct system
Sympathetic spinal reflex causes
Ducts and accessory glands to contract and empty their contents
Bladder sphincter muscle to constrict, preventing the expulsion of urine
Bulbospongiosus muscles to undergo a rapid series of contractions

25. Spermatogenesis
Sequence of events that produces sperm in the seminiferous tubules of the testes
Most body cells are diploid (2n) and contain
Two sets of chromosomes (one maternal, one paternal)
23 pairs of homologous chromosomes
Gametes are haploid (n) and contain
23 chromosomes

26. Spermatogenesis Spermatic cells give rise to sperm Mitosis Meiosis
Spermatogonia form spermatocytes
Meiosis
Spermatocytes form spermatids
Spermiogenesis
Spermatids become sperm

27. Figure 27.7a

28. Spermatogonium
(stem cell)
Cytoplasm of adjacent
sustentacular cells
Sustentacular
cell nucleus
Basal lamina
Type A daughter cell
remains at basal lamina
as a stem cell
Type B daughter cell
Tight junction between
sustentacular cells
Primary
spermatocyte
Secondary
spermatocytes
Early
spermatids
Late spermatids
Cytoplasmic
bridge
Spermatozoa
Lumen of
seminifer-
ous tubule
(c) A portion of the seminiferous tublule wall, showing the spermato-
genic cells surrounded by sustentacular cells (colored gold)
Figure 27.7c

29. Mitosis of Spermatogonia
Begins at puberty
Spermatogonia
Stem cells in contact with the epithelial basal lamina
Each mitotic division  a type A daughter cell and a type B daughter cell
Type A cells maintain the germ cell line at the basal lamina
Type B cells move toward the lumen and develop into primary spermatocytes

30. Basal lamina
Spermatogonium
(stem cell)
Type A daughter cell
remains at basal lamina
as a stem cell
Mitosis
Type B daughter cell
Growth
Enters meiosis I
and moves to
adluminal
compartment
Primary
spermatocyte
Meiosis I
completed
Secondary
spermatocytes
Meiosis II
Early
spermatids
Late spermatids
Spermatozoa
(b) Events of spermatogenesis,
showing the relative position
of various spermatogenic cells
Figure 27.7b

31. Sperm
Major regions
Head: genetic region; nucleus and helmetlike acrosome containing hydrolytic enzymes that enable the sperm to penetrate an egg
Midpiece: metabolic region; mitochondria
Tail: locomotor region; flagellum

32. Golgi apparatus Acrosomal vesicle
Approximately 24 days
Golgi
apparatus
Acrosomal
vesicle
Mitochondria
Acrosome
Nucleus 1 2
Centrioles
Spermatid
nucleus
Microtubules
Midpiece
Head
(a) 3
Flagellum
Excess
cytoplasm 4
Tail 5 6 7
(b)
Figure 27.8a, b

33. Hormonal Regulation of Male Reproductive Function
A sequence of hormonal regulatory events involving the hypothalamus, anterior pituitary gland, and the testes
Hypothalamus releases gonadotropin-releasing hormone (GnRH)
GnRH stimulates the anterior pituitary to secrete FSH and LH
FSH causes sustentacular cells to release androgen- binding protein (ABP), which makes spermatogenic cell receptive to testosterone
LH/ISCH stimulates interstitial cells to release testosterone
Testosterone is the final trigger for spermatogenesis
Feedback inhibition on the hypothalamus and pituitary results from
Rising levels of testosterone
Inhibin (released when sperm count is high)

34. GnRH Anterior Via portal pituitary blood Inhibin FSH LH Interstitial1
GnRH
Anterior
pituitary
Via portal
blood 8 7 2
Inhibin 2
FSH LH
Interstitial
cells 3 4 6
Testosterone
Somatic and
psychological
effects at
other body
sites
Sustentacular
cell
Spermatogenic
cells 5
Seminiferous
tubule
Stimulates
Inhibits
Figure 27.9

35. Male Secondary Sex Characteristics
Features induced in the nonreproductive organs by male sex hormones (mainly testosterone)
Appearance of pubic, axillary, and facial hair
Enhanced growth of the chest and deepening of the voice
Skin thickens and becomes oily
Bones grow and increase in density
Skeletal muscles increase in size and mass