The male reproductive system includes the testes, duct system, and accessory sex glands. The testes produce sperm and testosterone. Sperm mature as they move through the duct system, which includes the epididymis and vas deferens. The ductus deferens joins the seminal vesicles and prostate to form the ejaculatory ducts, which empty into the urethra. During ejaculation, the seminal vesicles and prostate gland secrete fluids that combine with sperm to form semen. The scrotum and penis are supporting structures that regulate temperature and allow delivery of semen during intercourse.

1. PREPARED BY: JEGAN.S.NADAR

2. The organs of male reproductive system include
1. Testes
2. A system of ducts
 The epididymis,
 Ductus deferens,
 Ejaculatory ducts, and
 Urethra
3. Accessory sex glands
 Seminal vesicles,
 Prostate, and
 Bulbourethral glands
4. Supporting structures
 Scrotum
 Penis Jegan

3. GENERAL ANATOMY OF THE MALE REPRODUCTIVE SYSTEM

4. SUPORTING STRUCTURES
JSN Jegan

5. SCROTUM
 The scrotum the supporting structure for the testes consists of loose skin hanging from the
root (attached portion) of the penis
 Externally, the scrotum looks like a single pouch of skin separated into lateral portions by a
median ridge called the raphe
 Internally, the scrotal septum divides the scrotum into two sacs, each containing a single
testis
 The septum is made up of a subcutaneous layer and muscle tissue called the dartos muscle
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6.  Associated with each testis in the scrotum is the cremaster muscle, a series of
small bands of skeletal muscle that descend through the spermatic cord to
surround the testes.
 The location of the scrotum and the contraction of its muscle fibers regulate
the temperature of the testes
 Normal sperm production requires a temperature about 2–3 C below core
body temperature
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7. Anterior view of scrotum and testes and transverse section of penis
Cremaster muscle
Spermatic cord
Scrotal septum
Cremaster muscle
Dartos muscle
Skin of scrotum
Raphe
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8. PENIS
 The penis contains the urethra and is a passageway for the ejaculation of
semen and excretion of urine
 It is cylindrical in shape and consists of
 a body,
 glans penis, and
 a root
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9. (a) Frontal section
Internal urethral orifice
External urethral orifice
Prostatic urethra
Bulbourethral (Cowper’s) gland
Deep muscles of perineum
BODY OF PENIS:
Corpora cavernosa penis
Corpus spongiosum penis
Spongy (penile) urethra
Urinary bladder
Prostate
Orifice of ejaculatory duct
Membranous urethra
ROOT OF PENIS:
Bulb of penis
Crus of penis
Frontal
plane
Corona
GLANS PENIS
Prepuce (foreskin)
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10. 1. THE BODY OF THE PENIS
 The body of the penis is composed of three cylindrical masses of tissue
 Tunica Albuginea
 Corpora Cavernosa Penis
 Corpus Spongiosum Penis
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11. (a) Frontal section
BODY OF PENIS:
Frontal
plane
Corpus spongiosum penis
Corpora cavernosa penis
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13. 2. GLAN PENIS
 The distal end of the corpus spongiosum penis is a slightly enlarged, acorn-
shaped region called the glans penis
 Its margin is the corona
 The distal urethra enlarges within the glans penis and forms a terminal
slitlike opening, the external urethral orifice.
 Covering the glans in an uncircumcised penis is the loosely fitting prepuce
or foreskin.
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14. (a) Frontal sectionExternal urethral orifice
Frontal
plane
Corona
GLANS PENIS
Prepuce (foreskin)
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15. 3. THE ROOT OF THE PENIS
 It is the attached proximal portion
 It consists of the
 Bulb of the penis
 Crura of the penis
 The bulb of the penis is attached to the inferior surface of the deep
muscles of the perineum and is enclosed by the bulbospongiosum muscle, a
muscle that aids ejaculation
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16. (a) Frontal section
Prostatic urethra
Bulbourethral (Cowper’s) gland
Deep muscles of perineum
Membranous urethra
ROOT OF PENIS:
Bulb of penis
Crus of penis
Frontal
plane
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17. SUPORTING STRUCTURES
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18. TESTES OR TESTICLES
 Paired oval glands in the scrotum
 Develops near kidney and descends through inguinal canals near 7th month of fetal
development
 Tunica vaginalis partially covers testes
 Tunica albuginea – internal to tunica vaginalis
 Tunica albuginea extends inward forming septa that divide testis into many lobules
 Each of 200-300 lobules contains 1-3 seminiferous tubules
 Sperm are produced here through spermatogenesis Jegan

19. (a) Sagittal section of testis showing seminiferous tubules
Blood vessels
and nerves
Head of epididymis
Seminiferous tubule
Straight tubule
Tunica vaginalis
Tunica albuginea
Lobule
Septum
Sagittal
plane
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20. SEMINIFEROUS TUBULE
The seminiferous tubules contain 3 types of cells:
1. Spermatogenic cells – sperm-forming cells
 Spermatagonia (stem cell) develop from primordial germ cells that arise in yolk sac
and enter testes in 5th week of development
 Primary spermatocytes → secondary spermatocytes → spermatids → sperm cells →
lumen
2. Sertoli cells or sustentacular cells– support cells
 Tight junction form blood-testis barrier – prevents immune response against sperm cell
surface antigens
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21.  Nourish spermatocytes, spermatids and sperm,
 Phagocytize excess spermatid cytoplasm,
 Control movements of spermatogenic cells, release sperm into lumen,
 Produce fluid for sperm transport,
 Secrete inhibin, regulate effects of testosterone and follicle-stimulating
hormone (FSH)
3. Leydig (interstitial) cells
 It is found in spaces between seminiferous tubules
 Secrete testosterone
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22. (b) Transverse section of part of seminiferous tubule
SPERMATOGENIC CELLS:
Spermatogonium (2n)
(stem cell)
Primary spermatocyte (2n)
Spermatid (n)
Sperm cell or
spermatozoon (n)
Secondary spermatocyte (n)
Leydig cell
Blood capillary
Basement membrane
Blood–testis barrier
(tight junction)
Lumen of seminiferous tubule
Sertoli cell nucleus
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23. SPERMATOGENESIS
 Takes 65-75 days
 Begins with spermatogonia – diploid (2n)
 Spermatogonia are type of Stem cells which undergo mitosis to replace themselves
(reservior for future) and some continue development
 Primary spermatocytes – diploid (2n)
 Each duplicates its DNA and meiosis begins
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24.  Meiosis I – homologous pairs line up, crossing over occurs
 Secondary spermatocytes (haploid or n)
 2 cells at end of Meiosis I
 Each chromosome made up of 2 chromatids attached at centromere
 Meiosis II – 2 chromatids separate
 Spermatids – 4 haploid cells at end of meiosis II
 Cells remain attached to each other by cytoplasmic bridges
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25. Jegan

26. Copyright 2009, John Wiley & Sons, Inc. Jegan

27. Spermatids Sperm cells
Secondary
spermatocyte
Second meiotic
division
First meiotic
division
(23 chromosomes, each
with 2 chromatids)
Paired homologous
chromosomes
(46 chromosomes,
each with 2 chromatids)
(23 chromosomes, each
with 2 chromatids) (23 chromosomes,
each chromatid now an
independent chromosome)
Primary
spermatocyte
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28. Jegan

29.  SPERMIOGENESIS
 Development of spermatids into sperm
 Spherical spermatids transform into elongated sperm
 Acrosome and flagella form, mitochondria multiply
 Sertoli cells dispose of excess cytoplasm
 SPERMIATION – release from connections to Sertoli cells
 Not yet able to swim
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30. SPERM
 Each day about 300 million sperm complete spermatogenesis
 The major part of sperm are head and tail
 Head
 4-5µm long
 Nucleus with 23 chromosomes (haploid or n)
 Acrosome – vesicle filled with oocyte penetrating enzymes
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31.  Tail
Neck – contains centrioles forming microtubules that comprise remainder of tail
Middle piece – contains mitochondria
Principal piece – longest portion of tail
End piece – terminal, tapering portion of tail
Once ejaculated,
sperm do not
survive more than
48 hours in female
reproductive tract
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32. HEAD
TAIL
Acrosome
Nucleus
Neck
Mitochondria
Middle piece
Principal
piece
End piece
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33. Facts
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34. Jegan

35. HORMONAL CONTROL OF TESTES
 At puberty, secretion of gonadotropin-releasing hormone (GnRH) increases
 GnRH Stimulates anterior pituitary to increase secretion of luteinizing hormone
(LH) and follicle-stimulating hormone (FSH)
 LH stimulates Leydig cells to secrete testosterone
 Synthesized from cholesterol mainly in testes
 Suppresses secretion of LH and GnRH via negative feedback
 Enzyme 5-alpha-reductase converts testosterone into dihydrotestosterone (DHT) in
external genitals and prostate
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36.  FSH acts indirectly to stimulate spermatogenesis
 FSH and testosterone act on Sertoli cells to stimulate secretion of androgen-binding
protein (ABP)
 ABP binds testosterone keeping concentration high
 Testosterone stimulates spermatogenesis
 Sertoli cells release inhibin which inhibits FSH
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37. Hypothalamus
GnRH
Testosterone decreases
release of GnRH and LH
Anterior pituitary
Gonadotroph
LH stimulates
testosterone secretion
Together with
testosterone, FSH
stimulates
spermatogenesis
Inhibin decreases
release of FSH
Inhibin
ABP
Spermatogenic
cells
Sertoli cells secrete
androgenbinding
protein (ABP)
Dihydrotestosterone
(DHT)
Leydig cells secrete
testosterone
FSH LH
LH
LH receptor
FSH
FSH receptor
Testosterone
Androgen
receptor
Key:
• Male pattern of development (before birth)
• Enlargement of male sex organs and expression of
male secondary sex characteristics (starting at
puberty)
• Anabolism (protein synthesis)
Testosterone
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38. SUPORTING STRUCTURES
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REPRODUCTIVE SYSTEM
DUCTS IN MALES
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39. REPRODUCTIVE SYSTEM DUCTS IN MALES
1. Ducts of testis
 Pressure generated by fluid produced by Sertoli cells push sperm along
seminiferous tubules into straight tubules
rete testis
efferent ducts in epididymis
ductus epididymis
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40. (a) Sagittal section of testis showing seminiferous tubules
Seminiferous tubule
Straight tubule
Sagittal
plane
Efferent duct
Rete testis
Tail of epididymis
Ductus epididymis
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41. 2. Epididymis
 Consists of tightly coiled ductus epididymis
 Has Head, body, tail
 Tail continues as ductus (vas) deferens
 Stereocilia are microvilli that reabsorb degenerated sperm
 It is site of sperm maturation – acquire motility and ability to fertilize
 It can store sperm for several months
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42. (a) Sagittal section of testis showing seminiferous tubules
Spermatic cord
Blood vessels
and nerves
Head of epididymis
Seminiferous tubule
Straight tubule
Tunica vaginalis
Tunica albuginea
Lobule
Septum
Sagittal
plane
Ductus (vas) deferens
Efferent duct
Rete testis
Body of epididymis
Tail of epididymis
Ductus epididymis
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43. 3. Ductus (vas) deferens
 45cm long
 Ascends posterior border of epididymis through spermatic cord
 The dilated terminal portion of the ductus deferens is the ampulla
 Conveys sperm during sexual arousal through peristaltic contractions
 Can also store sperm for several months
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44. 4. Spermatic cord
 Ascends out of scrotum
 It Consists of
 Ductus deferens as it ascends through scrotum,
 Testicular artery and veins that drain testes and carry testosterone into
circulations,
 Autonomic nerves,
 Lymphatic vessels, and
 Cremaster muscle Jegan

45. View
Left ureter
Urinary bladder
Hip bone (cut)
Prostate
Prostatic urethra
Membranous (intermediate)
urethra
Crus of penis
Bulb of penis
Corpus spongiosum penis
Right ductus
(vas) deferens
Ampulla of ductus
(vas) deferens
Seminal vesicle
Seminal vesicle duct
Ejaculatory duct
Deep muscles of perineum
Bulbourethral (Cowper’s) gland
Corpora cavernosa penis
Spongy (penile) urethra
(a) Posterior view of male accessory organs of reproduction
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46. 5. Urethra
 20cm long
 Shared terminal duct of reproductive and urinary systems
 Subdivided into
 Prostatic urethra. 2-3 cm long
 Membranous urethra. 1 cm long
 Spongy (penile) urethra. 15-20 cm long
 Ends at external urethral orifice
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47. View
Urinary bladder
Spongy (penile) urethra
(a) Posterior view of male accessory organs of reproduction
Prostatic urethra
Membranous
(intermediate) urethra
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48. SUPORTING STRUCTURES
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ACCESSORY SEX
GLANDS
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49. ACCESSORY SEX GLANDS
Accessory sex glands – secrete most of liquid portion of semen
1. Seminal vesicles
 The paired seminal vesicles or seminal glands are convoluted pouchlike structures
 About 5 cm (2 in.) in length
 Lying posterior to the base of the urinary bladder and anterior to the rectum
 Secrete alkaline, viscous fluid containing fructose, prostaglandins, and clotting proteins
(different from blood)
 About 60% of semen volume Jegan

50. View
Left ureter
Urinary bladder
Hip bone (cut)
Prostate
Prostatic urethra
Membranous (intermediate)
urethra
Crus of penis
Bulb of penis
Corpus spongiosum penis
Right ductus
(vas) deferens
Ampulla of ductus
(vas) deferens
Seminal vesicle
Seminal vesicle duct
Ejaculatory duct
Deep muscles of perineum
Bulbourethral (Cowper’s) gland
Corpora cavernosa penis
Spongy (penile) urethra
(a) Posterior view of male accessory organs of reproduction
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51. 2. Prostate
 The prostate is a single, doughnut-shape gland
 It measures about 4 cm from side to side, about 3 cm from top to bottom.
 It is inferior to the urinary bladder and surrounds the prostatic urethra
 Secretes milky, slightly acidic fluid containing
 Citric acid,
 Several proteolytic enzymes ( lysozyme, amylase, hyaluronidase),
 Acid phosphatase,
 Seminalplasmin (antibiotic)
 About 25% of semen volume
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52. View
Left ureter
Urinary bladder
Hip bone (cut)
Prostatic urethra
Membranous (intermediate)
urethra
Crus of penis
Bulb of penis
Corpus spongiosum penis
Right ductus
(vas) deferens
Ampulla of ductus
(vas) deferens
Seminal vesicle
Seminal vesicle duct
Ejaculatory duct
Deep muscles of perineum
Bulbourethral (Cowper’s) gland
Corpora cavernosa penis
Spongy (penile) urethra
(a) Posterior view of male accessory organs of reproduction
Prostate
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53. 3. Bulbourethral glands
 The paired bulbourethral glands are also known as cowpers gland
 They are located inferior to the prostate
 During sexual arousal, the bulbourethral glands secrete an alkaline fluid into the urethra
that protects the passing sperm by neutralizing acids from urine in the urethra
 They also secrete mucus that lubricates the end of the penis and the lining of the
urethra, decreasing the number of sperm damaged during ejaculation
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54. View
Left ureter
Urinary bladder
Hip bone (cut)
Prostate
Prostatic urethra
Membranous (intermediate)
urethra
Crus of penis
Bulb of penis
Corpus spongiosum penis
Right ductus
(vas) deferens
Ampulla of ductus
(vas) deferens
Seminal vesicle
Seminal vesicle duct
Ejaculatory duct
Deep muscles of perineum
Bulbourethral (Cowper’s)
gland
Corpora cavernosa penis
Spongy (penile) urethra
(a) Posterior view of male accessory organs of reproduction
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55. SEMEN
 Mixture of sperm and seminal fluid
 Typical volume 2.5-5 mL with 50-150 million sperm/mL
 Slightly alkaline pH of 7.2-7.7 due to seminal vesicle secretions
 Provides transport medium, nutrients, and protection
 Coagulates within 5 mins after ejaculation due to clotting proteins
 After about 10 to 20 minutes, semen reliquefies because prostate-specific antigen
(PSA) and other proteolytic enzymes produced by the prostate break down the clot
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