Spermatogenesis

Question 1

What are spermatogonia?

Answer 1

The ‘raw material’ for spermatogenesis

Question 2

How long are spermatogonia available for?

Answer 2

Up to 70 years

Question 3

How do spermatagonia divide?

Answer 3

Mitosis

Question 4

What does mitotic division of spermatogonia give rise to?

Answer 4

• Ad spermatogonium
• Ap spermatogonium

Question 5

What do Ad spermatagonium do?

Answer 5

Maintain stock

Question 6

What do Ap spermatagonium do?

Answer 6

Give rise to primary spermatocytes

Question 7

What happens to primary spermatocytes?

Answer 7

They divide by meiosis, giving rise to secondary spermatocytes

Question 8

What do secondary spermatocytes give rise to?

Answer 8

Spermatids

Question 9

What does each primary spermatocyte form?

Answer 9

4 haploid spermatids

Question 10

What happens to spermatids once produced?

Answer 10

They are released into the lumen of the seminiferous tubules in a process called spermination

Question 11

What happens to the spermatids as they pass down the seminiferous tubule?

Answer 11

They remodel

Question 12

What path do spermatids take from the seminiferous tubule?

Answer 12

They pass through the rete testis and ductuli efferentes

Question 13

Are sperm motile when passing through the seminiferous tubule to the ductuli efferentes?

Answer 13

No

Question 14

If spermatids are non-motile, how can they pass through the seminiferous tubules to ductuli efferentes?

Answer 14

Transport via Sertoli cell secretions, assisted by peristaltic contraction, until they reach the epididymis

Question 15

What happens to spermatids in the epididymis?

Answer 15

They form spermatozoa

Question 16

What is sperm capacitation?

Answer 16

The final maturation step required before sperm become fertile

Question 17

Where does sperm capacitation happen?

Answer 17

In the female genital tract

Question 18

What happens in sperm capacititation?

Answer 18

• Removal of glycoproteins and cholesterol from sperm membrane
• Activation of sperm signalling pathways

Question 19

What is involved in the activation of sperm signalling pathways?

Answer 19

Atypical soluble adenylyl cyclase and PKA

Question 20

What does sperm capacitation allow?

Answer 20

Sperm to bind to zona pellucida of oocyte and initiate aerosome reaction

Question 21

What must happen to human sperm for in vitro fertilisation?

Answer 21

It must first be incubated in capacitation media

Question 22

What is the spermatic cycle defined as?

Answer 22

The time taken for reappearance of the same stage within a given segment of tubule

Question 23

How long is the spermatic cycle in humans?

Answer 23

About 16 days

Question 24

Why does the spermatic cycle occur?

Answer 24

Because not all stages in spermatogenesis are visible in a single cross-section of the seminiferous tubule

Question 25

Why are not all stages in spermatogenesis not visible in a single cross-section of the seminiferous tubule?

Answer 25

Cells tend to appear in groups with the same maturation stages

Question 26

What is the spermatogenic wave?

Answer 26

The distance between the 'same stage'

Question 27

Why can the spermatogenic wave be defined?

Answer 27

Because different stages in spermatogenesis are ordered in time as well as space, and each stage follows an orderly sequence along the length of the tubule

Question 28

What is the rete testis?

Answer 28

Part of the testis

Question 29

What is the role of the rete testis?

Answer 29

Spermatids move down rete testis to reach epididymis

Question 30

What is the epididymis the location for?

Answer 30

Spermatozoa formation

Question 31

Is the epididymis part of the testis?

Answer 31

yes

Question 32

What structures are involved in the delivery of sperm?

Answer 32

* Seminal vesicles * Prostate * Bulbourethral glands * Vas deferens

Question 33

How does sperm enter semen?

Answer 33

It travels down the vas deferens

Question 34

What % of semen does seminal vesicle secretions constitute?

Answer 34

70%

Question 35

What do seminal vesicle secretions consist of?

Answer 35

* Amino acids * Citrate * Fructose * Prostaglandins

Question 36

What % of semen do prostate secretions constitute?

Answer 36

25%

Question 37

What do prostate secretions consist of?

Answer 37

* Proteolytic enzymes * Zinc

Question 38

What are bulbourethral glands also called?

Answer 38

Cowper glands

Question 39

What % of semen does bulbourethral glands secretions constitute?

Answer 39

1%

Question 40

What do bulbourethral gland secretions consist of?

Answer 40

Mucoproteins

Question 41

What is the function of mucoproteins?

Answer 41

* Helps lubricate * Neutralises acidic urine in distral urethra