Male reproductive system anatomy

1. Male Reproductive System
Kanwal Asif
Lecturer RLCP
MPhil (Pharmacology)

2. General Terminologies & Concept
Gonads: Primary reproductive organ i.e. Testes (Male) &
Ovaries (Female)
Gonads perform dual function:
(1) Gametogenesis is the production of the reproductive
cells, or gametes; these are spermatozoa/sperm by
males and ova (singular, ovum) by females.
(2) The gonads secrete particular steroid hormones, often
termed sex hormones; the primary sex hormones are
testosterone in the male and estradiol and
progesterone in the female.

3. Accessory reproductive organs: Systems of
ducts through which the sperm or eggs are
transported and the glands lining or emptying
into the ducts.
Secondary sexual characteristics : comprise
the many external differences—hair
distribution and body contours, for example—
between males and females. The secondary
sexual characteristics are not directly involved
in reproduction.

4. Hormones controlling Reproduction

5. Stages in control of Reproductive Functions

6. General Principles of Gametogenesis
 At any point in gametogenesis, the developing gametes are
termed germ cells.
 These cells undergo either mitosis or as meiosis.
 I. The first stage of gametogenesis is mitosis of germ cells.
 II. This is followed by meiosis, a sequence of two cell
divisions resulting in each gamete receiving 23
chromosomes.
 III. Crossing-over and random distribution of maternal
and paternal chromatids to the daughter cells during
meiosis cause genetic variability in the gametes.

7. Spermatogenesis:

8. Human Mature Sperm

9. Transport of Sperm:
 I. From the seminiferous tubules, the sperm pass
through the epididymis, where they are concentrated.
 II. The epididymis and vas deferens store the sperm,
and the seminal vesicles and prostate secrete the bulk
of the semen.
 III. Erection of the penis occurs because of vascular
engorgement accomplished by relaxation of the small
arteries and passive occlusion of the veins.
 IV. Ejaculation includes emission—emptying of
semen into the urethra—followed by expulsion of the
semen from the urethra.

10. Male Reproductive System
 Organs of male reproductive system
 Testis:
 Seminiferous tubules
 Interstitial cells
 Spermatic Ducts:
 Epididymides
 Ductus deferentia
 Ejaculatory ducts

11. Male Reproductive System
 Organs of male reproductive system
contd:
 Accessory Reproductive Glands:
 Seminal Vesicles.
 Prostate gland.
 Bulbourethral glands.
 Scrotum
 Penis

12. Male Reproductive System

13. Male Reproductive System
 TESTES:
 Located within the scrotum, the testes produce
spermatozoa and androgens. Androgens regulate
spermatogenesis and the development and functioning
of the secondary sex organs.
 Structure of Testes:
 The testes are paired, whitish, ovoid organs, each about
4 cm (1.5 in.) long and 2.5 cm (1 in.) in diameter. Two
tissue layers, or tunics, cover the testes.

14. Male Reproductive System
 Tunica Vaginalis:
 Tunica vaginalis is a thin serous outer sac derived from the
peritoneum during the descent of the testes.
 Tunica Albuginea:
 The tunica albuginea is a tough fibrous membrane that
directly encapsulates each testis
 Testicular Lobules:
 Fibrous inward extensions of the tunica albuginea partition
the testis into 250 to 300 wedge-shaped testicular lobules.

15. Male Reproductive System
 Seminiferous Tubules:
 Each lobule of the testis contains tightly convoluted
seminiferous tubules, that may exceed 70 cm (28 in.) in
length if uncoiled. The seminiferous tubules are the functional
units of the testis because it is here that spermatogenesis, the
production of spermatozoa, occurs.
 Sustentacular (Sertoli) Cells:
 Forming the walls of the seminiferous tubules are
sustentacular (Sertoli) cells (also called nurse cells) that
produce and secrete nutrients for the developing spermatozoa
embedded between them.

16. Male Reproductive System
 Interstitial Cells (cells of Leydig):
 Between the seminiferous tubules are specialized endocrine
cells called interstitial cells (cells of Leydig). The function of
these cells is to produce and secrete the male sex hormones.
The testes are thus considered mixed exocrine and endocrine
glands because they produce both spermatozoa and
androgens.

17. Male Reproductive System

18. Male Reproductive System
 Rete Testis:
 The rete testis is an anastomosing network of delicate
tubules located in the hilum of the testicle that carries sperm
from the seminiferous tubules to the efferent ducts.
 Efferent Ductules:
 The spermatozoa are transported out of the testis and into the
epididymis through a series of ducts known as efferent
ductules.

19. Male Reproductive System
 Spermatic Ducts:
 The spermatic ducts store spermatozoa and transport
them from the testes to the urethra. The accessory
reproductive glands provide additives to the
spermatozoa in the formation of semen.
 Epididymis
 Ductus Deferens
 Ejaculatory Duct

20. Male Reproductive System
 Spermatic Ducts:
 Epididymis:
 Highly convoluted duct behind the testis, along which sperm
passes to the vas deferens. The upper expanded portion is the
head, and the tapering middle section is the body. The tail is
continuous with the beginning portion of the ductus deferens.
 Ductus Deferens:
 The ductus deferens is a fibromuscular tube about 45 cm (18
in.) long and 2.5 mm thick (see fig. 20.1) that conveys
spermatozoa from the epididymis to the ejaculatory duct. Also
called the vas deferens.
.

21. Male Reproductive System
 Ductus Deferens:
 The ampulla of the ductus deferens is the terminal portion that
joins the ejaculatory duct.
 Much of the ductus deferens is located within a structure known as
the spermatic cord.
 Ejaculatory Duct:
 The ejaculatory ducts (ductus ejaculatorii) are paired structures in
male anatomy. Each ejaculatory duct is formed by the union of the
vas deferens with the duct of the seminal vesicle. They pass through
the prostate, and open into the urethra at the seminal colliculus.
 The urethra serves as a passageway for both semen and urine. It is
the terminal duct of the male duct system.

22. Male Reproductive System
Accessory Reproductive Glands:
 The accessory reproductive glands of the male include
the seminal vesicles, the prostate, and the bulbourethral
glands. The contents of the seminal vesicles and prostate
are mixed with the spermatozoa during ejaculation to
form semen (seminal fluid). The fluid from the
bulbourethral glands is released in response to sexual
stimulation prior to ejaculation.

23. Male Reproductive System
 Accessory Reproductive Glands:
 Seminal Vesicles:
 The paired seminal vesicles, each about 5 cm long, are
convoluted club-shaped glands lying at the base of the urinary
bladder, in front of the rectum. They secrete a sticky, slightly
alkaline, yellowish substance that contributes to the motility
and viability of spermatozoa. The secretion from the seminal
vesicles contains a variety of nutrients, including fructose,
that provide an energy source for the spermatozoa. It also
contains citric acid, coagulation proteins, and prostaglandins.
The discharge from the seminal vesicles makes up about 60%
of the volume of semen

24. Male Reproductive System
 Accessory Reproductive Glands:
 Prostate Gland:
 A gland surrounding the neck of the bladder in male and
releasing a fluid component of semen. The thin, milky-
colored prostatic secretion assists sperm cell motility as a
liquefying agent, and its alkalinity protects the sperm in their
passage through the acidic environment of the female vagina.
The prostate also secretes the enzyme acid phosphatase,
which is often measured clinically to assess prostate function.
The discharge from the prostate makes up about 40% of the
volume of the semen.

25. Male Reproductive System
 Accessory Reproductive Glands
 Bulbourethral Glands:
 The paired, pea-sized, bulbourethral (Cowper’s) glands are
located below the prostate. Upon sexual arousal and prior to
ejaculation, the bulbourethral glands are stimulated to secrete
a mucoid substance that coats the lining of the urethra to
neutralize the pH of the urine residue. It also lubricates the tip
of the penis in preparation for coitus.

26. Male Reproductive System
Scrotum:
 The scrotum is an anatomical male reproductive
structure that consists of a suspended dual-chambered
sack of skin and smooth muscle and located under
the penis. Encloses and protects the testes; helps
maintain constant temperature for spermatogenesis.

27. Male Reproductive System
 PENIS:
 The penis when distended, serves as the copulatory
organ of the male reproductive system. The penis and
scrotum, which are suspended from the perineum,
constitute the external genitalia of the male. Under the
influence of sexual stimulation, the penis becomes
engorged with blood. This engorgement results from the
filling of intricate blood sinuses, or spaces, in the
erectile tissue of the penis. The human penis is an
external male intromittent organ that additionally
serves as the urinal duct.

28. Male Reproductive System
 Parts of Penis:
 Root of the penis (radix): It is the attached part,
consisting of the bulb of penis in the middle and
the crus of penis, one on either side of the bulb. It
lies within the superficial perineal pouch.
 Body of the penis (corpus) is made up of three
columns of tissue: two corpora cavernosa on
the dorsal side and corpus spongiosum between
them on the ventral side.
 Epithelium of the penis consists of the shaft skin,
the foreskin, and the preputial mucosa on the
inside of the foreskin and covering the glans penis.
The epithelium is not attached to the underlying
shaft so it is free to glide to and fro.

29. MALE REPRODUCTIVE SYSTEM