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Functions of the Male
Reproductive System
• Spermatogenesis
• Delivery of spermatozoa to female
• Production of male sex hormones
– Development of secondary male characteristics
– Development of sex drive (libido)

Reproductive Tract of Boar
• Large volume of ejaculate
produced by boar
______________
• Coitus is protracted in this
species (up to 30 minutes)
• Spiralling of end of penis
• End of penis believed to
enter uterus

Reproductive Tract of Bull
• ____ penis
• Spiralled at end
• Sigmoid flexure

1

• Prepuce protects non erect penis

Semen Collection Bull

Cryptorchidism

Anatomy of Testis

• Failure of Testes to Descend during prenatal life
– ____ of infants and ________ % of premature infants
– ↑ risk of testicular cancer
– __________ needs not met
– Endocrine function not impaired

•

Normal sexual drive but sterile

• ↑ ________ ___________
– temporary sterility of long distance runners, cyclists –
Don’t work with laptop on your knee!

• Testis- divided into 200-400 compartments by fibrous connective
tissue- lobules
• Each lobule contains 1-4 highly convoluted seminiferous tubules in
which sperm are formed
• Sperm prod
...
___________ cells
2
...
___________ cells
• Lie between _________ tubules
• Testosterone

2

Spermatozoa

Spermatogenesis
•

• Head

From Spermatogonia (2n) to mature Spermatozoa (n)
– Man ~____________

– Acrosome - Fertilisation

– Bull ~___________

– Haploid Nucleus - Condensed
DNA

– Ram ~____________

• Different stages of differentiation in each seminiferous tubule

• Midpiece
– ______________

• Spermatozoa may be present in some tubules and
predominantly spermatids or primary spermatocytes in others

– Mitochondria- ___________
Production (ATP for
locomotion)

• Each day ~_________ million sperm complete spermatogenesis

• Tail: Flagellum
– __________ Structure/Movement

Sertoli Cells -

Sertoli Cells - Functio ns

Functions

4
...
_________
–

Of the Seminiferous Tubule Cells –

– Androgen Binding Protein (ABP)

Once fully differentiated
the Sertoli cell is unable
to proliferate

– Inhibin
– Activin

Inner Tubule - Avascular
•

5
...
____________
Cytoplasmic Droplets from
Spermatids
–

Damaged Germ Cells

–

3
...
____________

•

– ⇑ growth of laryngeal cartilage- Adam’s apple

Stimulates spermatogenesis and
spermiogenesis

2
...
3 mg/day

– Improved Athletic Performance
– ⇑ BMI, ⇑ RBC Density, ⇑ Oxygen Utilizatio n

• In genetically susceptible men causes ‘Male pattern baldness’

Regulation of Testosterone
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Hormonal Control of the Testes
• At __________
–

Hypothalamus ↑

secretion of GnRH –

Secretion

Why ???
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__________
GnRH

• ______________
(puberty)

– Stimulates the
anterior pituitary

Anterior Pituitary

•

LH

FSH

•

FSH

LH

Activin/Inhibin

_______ Cells

_______ Cells

Sertoli Cells - Hormonal Functions
•
•

FSH stimulates Sertoli cells to express androgen binding protein
_______________ (ABP)
–
–
–

•

_________________
–
–

•

Secreted post puberty
Inhibits FSH

______________
–
–

•

Transports testosterone
Maintains Testosterone levels in seminiferous tubule
•
Essential for spermatogenesis
Facilitates sperm maturation

Secreted post puberty
Stimulates FSH
•
Modulate Spermatogenesis Via FSH

Convert Androgens to Estrogens
– Aromatase from sertoli cells convert testosterone to estrone & DHT
to direct spermatogenesis

–

Hormonal Modulation of Tubular Function

Pathways to pregnancy &
parturition
...
Senger

Anatomy of the Penis
Physiology of Penile Erec tion

Male Accessory Glands
1
...
__________ (x1) - Secretes about 30% of the Seminal Fluid

Reproductive function is to deposit semen in
female reproductive tract during intercourse

Erection

– Slightly acidic (PH ~6
...
______________ Glands (Cowper) (x2)
– Mucous, Alkaline Secretion
– Lubrication
– Transport and Neutralize the Acidic pH of Urethra

Ejaculation

Semen contains
1
...
______________ (99%)
• Reflex sensory nerves to spinal cord- impulses to:

– _________ monosaccharide used by mitochondria of sperm for
energy production

– Smooth muscle of ____________ and Vas deferens

• contract release sperm

– Buffer- neutralises acidic secretions of female reproductive tract

– Smooth muscle in walls of sex accessory glands

– ________ may stimulate uterine contractions- assist with movement
of sperm up female tract

• secretions into vas ______________ and urethra

– Smooth muscle contraction of urethra release of semen during
ejaculation

– Some lymphocytes (may be method of HIV viral spread)

Sperm Quality Tests

Volume & normal sperm concentration
•

Concentration

•

<20 million/ml = low sperm count

–
Ram

Bull

Boar

Stallion

Man

Man average ___________ million sperm/ml semen
– ↓ by 1-2% per year over the last 2 decades

5

Volume of ejaculate (ml)

1-2

5-8

200-250

50-100

2-4

•

Motility

2000-3000

800-2000

200-300

50-300

60

•

Morphology

________________________
Concentration of
spermatozoa
(10 6/ml)

__________

•
Number of spermatozoa
per ejaculate (x10 9)

1
...
5

5-15

30-60

5-15

120-240 x10 6

PH
–

•
tract???

_____________________

How long can sperm live in the female reproductive

6



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