1. Spermatogenesis (Spermatocytogenesis, Spermiogenesis, Spermiation, Shape and function of cells inside the Testis, Semen and sperm structure, Sperm journey after synthesis to outside)

1. Male
Reproductive Physiology
Dr. Yasmin Magdi Abd-Elkreem

2. Male Reproductive
SYSTEM
• Testis (Sperm and hormones)
• System of ducts (receive and transport
sperm)
(Epididymis, Vas deferens, ejaculatory ducts, and
urethra)
• Accessory sex glands (secrete fluids into
ducts)
(Seminal Vesicles, Prostate, and Bulbourethral
Glands)

3. The Male
Reproductive System
in Anterior View
The Male Reproductive
System in Midsagital View

4. Testis
Definition :- Is the male gonad in the human
-Paired organ
Function: 1. Produce male gametes (Spermatogenesis) in seniniferous tubules.
2. Produce steroid hormones (Steroidogensis) in interstitium.
3. Nourish the produced sperm.
Location : - Lowered in Lower abdomen in external pouch called scortum. (-2/3 ͦ
C)
- descended from abdomen into scrotum around week 28 of pregnancy.
Testicular Anatomy and Physiology:
1. External appearance :
Each testis weighs about 25 grams (0.875 ounce) and is 4–5 cm (1.6–2.0 inches)
long and 2–3 cm (0.8–1.2 inches) in diameter.
The testis descends from a retroperitoneal position through the inguinal canal to
take its place in the scrotum.

5. Testis
• Scrotum:
- consists of skin and subcutaneous tissue
- A vertical septum, of subcutaneous tissue
in the center divides it into two parts,
each containing one testis.
A]Smooth muscle fibers, called the dartos muscle, in the subcutaneous tissue
contract to give the scrotum its wrinkled appearance. When these fibers are
relaxed, the scrotum is smooth.
B]the cremaster muscle, consists of skeletal muscle fibers and controls the
position of the scrotum and testes. When it is cold or a man is sexually
aroused, this muscle contracts to pull the testes closer to the body for warmth.

6. Testis
2. Internal Structure :
- Each testis is an oval structure
- Covered by: tunica albuginea
- There are about 250 lobules in each testis.
Each contains 1 to 4 -seminiferous tubules that
converge to form a single straight tubule.
Seminiferous tubules
- comprise 95% of testicular volume, and are devoted to the production of
spermatozoa.
- Small, coiled tubes, each tubule is 30-70 cm long and 200-300 um in
diameter.
There are approximately 500 tubules per testis. The tubules are
divided by fibrous septae, and surrounded by the tough tunica
albuginea.

7. Testis
[Organization of the cells of the Seminiferous Epithelium:]
(1) SERTOLI CELLS : Nonreplicating physical support cells
Function : -Remove excess cytoplasm from developing spermatid - tubulobulbar
processes
- Move spermatids toward the lumen of the seminiferous tubules - ectoplasmic
specializations
- Nurture and mediate maturation of spermatids
- Segregate groups of developing gametes
- Secrete fluid to transport sperm in reproductive tract
- Secrete hormones and other factors
a.Embryonic - anti-mullarian hormone
b.Adult - inhibin -estrogen - Other factor (not a hormone) - androgen
binding protein (helps transport androgens from interstitial fluid into
seminiferous tubule -promotes spermatogenesis)

8. Testis
(2) MESENCHYMAL CELLS :
- Each seminiferous tubule is surrounded by mesenchymal cells, which
comprise the peritubular myoid cells whose contractile elements generate
peristaltic waves along the tubules, but do not present a tight diffusion barrier.
(3) INTERSTITIAL TISSUE
- located between the seminiferous tubules
- comprised of connective tissue, blood vessels,
lymphatics, and Leydig cells cells which produce
testosterone.

9. Testis
(4) SPERMATOGENIC CELLS :
-Stem cells which regularly replicate and
differentiate into mature sperm as they migrate
toward the lumen
Function: spermatogenesis continue the
spermatocytes progressively move
from basement membrane to the luminal
side of seminiferous tubule

10. Spermatogenesis
• Site of Sperm Formation :
-Occur in the seminiferous tubules in the testis
• The Sperm formulation involves three steps:
1. Spermatocytogenesis: spermtogenic cells form
rounded cells called spermatids
2. Spermiogenesis: spermatids which in the second step
differentiate into specialized cells known as sperms.
3. Spermiation

12. 1.Spermatocytogenesis:.Steps of Spermatocytogenesis:
1.The primitive sex cells appear earliest in 4th week of intra uterine life in the
wall of yolk sac as primordial germ cells They migrate to the developing
testes and lie dormant among the cells lining the seminiferous tubules.
2. At puberty the germ cells awaken and start the actual process of spermato
genesis
3..Spermatogonia are the Germ-Line cells. They are diploid (2n). They undergo
mitosis to reproduce themselves.(Increase in No.)
4. One of these spermatogonia undergoes meiosis, and it is called a primary
spermatocyte. It is diploid (2n).
5.The primary spermatocyte undergoes MEIOSIS I to produce two secondary
spermatocytes. These are now haploid (n) but still contain two chromatids per

13. 1.Spermatocytogenesis:
6..Each of these secondary spermatocytes undergoes MEIOSIS II to each
produce two spermatids. Spermatids are haploid (n) and each contain 1
chromosome that was previously a chromatid. The result is 4 total
spermatids.

14. 2.Spermiogenesis:
.Steps of Spermiogensis:
1.Spermatids modify to assume specific shape of the sperm.they elongate and
reorganize internal structure to acquire the particular shape.
2. The changes include ;
-Golgi apparatus forms acrosomal
cap-proteolitic enzymes
-Nucleus is condensed
-Centriols: make collar around neck
-Microtubules, forrm flagellum,
-Mitochondria arrange as spiral
around neck
-Excess cytoplasm cast off as residual
body
-Cytoplasmic bridges break and
sperms release from Sertoli cells to
lie free in lumen of seminiferous
tubules

15. 3.Spermiation:
• mature spermatids are released from Sertoli
cells into the seminiferous tubule lumen prior
to their passage to the epididymis.
• extensive restructuring and remodelling of the
spermatid to produce a streamlined
spermatozoan
• involves several discrete steps including
• 1. remodelling of the spermatid head and
cytoplasm
• 2. removal of specialized adhesion structures
• 3. the final disengagement of the spermatid
from the Sertoli cell.

16. Intra-Testicular Communication
(Regulation of spermatogenesis)
• cellular communication is categorized into:
1. Endocrine signaling is mediated by hormones.
- Hormones are transported via the bloodstream from the site of production, and
reach their cellular target through diffusion or mediated by receptor.
- Albeit indispensable ,highly effective and relatively slow.

18. Intra-Testicular Communication
2. Paracrine signaling
• level of interaction exists between the neighbouring cellular
elements.
• Not only signaling between neighboring cells but also between the
testicular compartments
• occur between immune cells, fibroblasts and Leydig cells in the
interstitiurn, between interstitial cells and peritubular cells, between
peritubular cells and Sertoli cells, between Sertoli cells and germ
cells and among germ cells themselves.
3. Autocrine signaling.
• the secreted molecules that act back on the cells from which they
originate.
A signaling molecule can functionally cover more than one
category.

19. Rete testis
- Fully formed spermatozoa leave the seminiferous tubules by straight
tubules and enter interconnected channels called rete testis within
the mediastinum (bottom left).
- The rete testis lead into the efferent ductules (bottom right) that
lead into the head of the epididymis.
- Note the cells of Efferent ductules have cilia, which beat to help
move mature sperm to the epididymis.

20. Epididymis
Definition :- a long, coiled tube.
- Transportation, Storage and maturation area for sperm.
- Efferent ductules empty into epididymis.
Functions:.
1. Maturational changes of spermatozoa
2. Stabilization of condensed chromatin.
3. Changes in surface charge of the plasma membrane.
4. New sperm surface proteins.
5. Sperm storage.
6. Sperm transport by peristalsis (sperm epididymal maturation requires
2-12 days).
7. Release of spermatozoa during ejaculation.
8. Elimination of aged
Location : - a curved structure on the posterior (back) margin of each
testis.
-Scalloped outline.

21. Epididymis
Epididymal Anatomy and Physiology:
-The efferent ducts fuse to form the ductusepididymidis
of the epididymis.
- Single highly coiled tube (4-6 m).
- The canal is surrounded by connective tissue
and blood vessels.
divided into four gross anatomical regions:
- the initial segment,
- head (caput),
- body (corpus),
- and tail (cauda)
Caput
Corpus
Cauda

22. Ductus (Vas) deferens
• Upon ejaculation the epididymis contracts, expelling sperm into the ductus
deferens.
• Can also store sperm several months
• Ampulla of the vas deferens
• After the ductus deferens exits the deep inguinal canal, it heads superiorly
towards the urinary bladder.
• Terminal portion of the vas deferens enlarges into an ampulla.
• Lumen of ampulla larger than vas deferens.
• After crossing the ureters, the ampulla of the ductus deferens joins the
seminal vesicle.

23. Accessory sex glands
• The male reproductive system includes three different
accessory sex glands, namely a pair of seminal vesicles, a pair
of bulbourethral glands and the prostate.
• Their secretions provides the bulk of semen.
• 4 Major Functions of Male Glands
1. Activating spermatozoa.
2. Providing nutrients spermatozoa need for motility.
3. Propelling spermatozoa and fluids along reproductive tract:
mainly by peristaltic contractions.
4. Producing buffers: to counteract acidity of urethral and
vaginal environments

24. 1. Seminal vesicles (glandulae
vesiculosae)
Definition :- Paired, elongated, saclike structures, and highly
folded tubular gland.
- The duct of each joins with the distal end of
the ductus deferens to form an ejaculatory duct.
- Empty its secretions into vas deferens.
Functions:
1. secrets a strongly acidophilic and
constitutes 45-80 % of the ejaculate volume
(2-2.5 mL).
2. Its secrets contains several proteins, enzymes, mucus
and vitamin C.
3. Rich in Fructose ( major sourse of energy)
Location : -
On posterior wall of urinary bladder.

25. 2. Prostate
Definition :- The largest accessory gland consisting
of 30-50 branched tubuloalveolar glands.
Empty its secresions in the urethra.
Functions:-
1. Secretions are acidic (pH 6.5).
2. Prostatic fluid contributes 15-30 % or about 0.5 mL to the volume of the
semen.
3. Contains a high citric acid content (maintain the osmotic equlibirium in
semen) , acid phosphatase and zinc.
4. Contains enzymes required for liquefaction of the ejaculate coagulum.
Location : -
- surrounds and opens into the urethra where it leaves the bladder.

26. 3. Bulbourethral glands (Cowper´s
glands)
• Definition :- pair of pea-sized structures
• Functions:
• 1. Secretions including galactose, sialic acid
• 2. has a lubrication function (mucoprotiens) and precedes emission of
semen along the penile urethra.
• 3. forming a part of the ejaculate (0.1-0,2 mL = 5%)
• Location : -located in the urogenital diaphragm, close to the bulb of
the penis.

27. Ejaculatory duct
- Is a short passageway (2 cm): at junction of ampulla and seminal vesicle
duct.
- Penetrates wall of prostate gland.
- Empties into urethra.
Urethra
• Passageway for urine and male reproductive fluids
• Extends 18–20 cm: Extends from urinary bladder to distal end (tip) of
penis.
• Is divided into 3 regions:
– prostatic
– membranous
– spongy

28. Penis
• Contains urethra
• Passageway for ejaculation of semen and excretion of
urine.
• Body of penis – 3 cylindrical masses of tissue with
erectile tissue:
• Glans penis – terminal opening is external urethral orifice
• Prepuce or foreskin covers glans in uncircumcised men
• Root of penis is attached portion
• Erection – parasympathetic fibers release and cause local production of
nitric oxide (NO) causing smooth muscle in arterioles to relax and
dilate allowing large amounts of blood to enter penis

29. Points to Remember
Sperm Summary
• Produced: Seminiferous tubules (Testis).
• Stored: Epididymis
• Transported through epididymis by rhythmic
peristaltic contractions as they mature
• Epididymis Vas Deferens  Ejaculatory
duct (ampulla of vas deferens fuses with duct
of seminal vesicle “ejaculatory duct”) 
prostate prostatic urethra (then passes the
bulbourethral gland) membranous urethra 
penile urethra

30. Points to Remember

32. Spermatozoon
- Each day about 300 million sperm complete spermatogenesis
The human sperm cell is about 70 µm long
- Head
- Nucleus with 23 chromosomes (haploid or n)
- Acrosome – vesicle filled with oocyte penetrating enzymes
- It is the head which binds to the egg at fertilization
- Midpiece:
- the energy for motility is generated by mitochondria
- Tail:
- motility – the beat is initiated just behind the midpiece, and then propagated along
the tail
– Once ejaculated, sperm do not survive more than 48 hours in female
reproductive tract.

34. At the end of lecture you are able
to
• Describe the structure of the testis and the process of
spermatogenesis.
• What is spermatogenesis?
• Sperm production and pathway.
• Describe the sperm structure.

35. References
1. 2014 Andrology and Embryology Review Course
Manual of the American Board of Bioanalysis (ABB).
2. Robaire B, Hinton BT, Orgebin-Crist M, The
Epididymis. In: Knobil and Neill’s Physiology of
Reproduction,Third Edition edited by Jimmy D. Neill.
Elsevier © 2006. 1071-1148.

36. Thank You
For contact: Yas.magdi@hotmail.com