Spermatogenesis

Question 1

Where are sperm made and stored?

Answer 1

→ In the testes

→ stored in the epididymis

Question 2

What contracts during ejaculation?

Answer 2

→ The vas deferens

Question 3

Where do the sperm travel to after the vas deferens?

Answer 3

→ Seminal vesicle which contribute seminal fluid

→ move to the prostate which also contribute secretions

Question 4

Where does the vas deferens meet the urethra?

Answer 4

→ In the prostatic gland

Question 5

What is responsible for erections?

Answer 5

→ Hydrostatic pressure

Question 6

Where are the testes located?

Answer 6

→ in the scrotum outside the body cavity

Question 7

Why are the testes located outside the body?

Answer 7

→ Optimum temperature for sperm production

→ overheating reduces sperm count

Question 8

What is the normal volume of the testes and how is this measured?

Answer 8

→ 15-25ml

→ orchidometer

Question 9

What do the tubules lead to?

Answer 9

→ Rete on one side

Question 10

What does the rete lead to?

Answer 10

→ Epididymis and vas deferens

Question 11

What is 90% of the testis made up of?

Answer 11

→ seminiferous tubules

Question 12

Where is the site of spermatogenesis?

Answer 12

→ Seminiferous tubules

Question 13

How long does it take for sperm to go from the basal side to the lumen?

Answer 13

→ 74 days

Question 14

What are sertoli cells held together by?

Answer 14

→ Tight junctions

Question 15

What are tight junctions for?

Answer 15

→ preventing an immune response against sperm cells

Question 16

Describe the formation of spermatozoa

Answer 16

→ The sperm start as spermatogonia which are diploid
→ they replicate by mitosis and form 2 types of cell
→ type A and type B
→ type A is used as the template and replicates again
→ type B moves into the adluminal compartment and becomes a primary spermatocyte
→ the primary spermatocyte undergoes meiosis I and become secondary spermatocyted
→ 2ndary spermatocytes divide to form 4 daughter cells (meiosis II)
→ these are spermatids

Question 17

What are the walls of the seminiferous tubules made from?

Answer 17

→ Tall columnar endothelial cells which are Sertoli cells

Question 18

What are spaces between the seminiferous tubules filled with?

Answer 18

→ blood
→ lymphatic vessels
→ Leydig cells

Question 19

How long does the cycle of spermatogenesis take?

Answer 19

→ 74 days

Question 20

How often do new cycles of spermatogenesis occur?

Answer 20

→ every 16 days

Question 21

Summarise spermatogenesis in 3 steps?

Answer 21

→ mitotic proliferation of spermatogonia
→ Meiosis and development of spermatocytes
→ spermiogenesis , elongation, loss of cytoplasm and movement of cellular content

Question 22

What do spermatids remain connected by and why?

Answer 22

→ A cytoplasmic bridge

→ they form a syncytium allowing synchronous development

Question 23

What are the 2 differences between oogonia and spermatogonia?

Answer 23

→ Cannot make more oocytes by mitosis
→ sperm can divide mitotically
→ limited supply of eggs

Question 24

What do Leydig cells do?

Answer 24

→ LH binds

→ Convert cholesterol into testosterone

Question 25

What receptors do Sertoli cells have?

Answer 25

→ FSH

Question 26

What is the function of Leydig and Sertoli cells?

Answer 26

→ Leydig cells make testosterone | → Sertoli cells make ABP which makes testosterone more soluble so it can be concentrated in the lumen

Question 27

What happens if you take anabolic steroids?

Answer 27

→ Decrease in LH and FSH | → Testicular atrophy occurs

Question 28

What happens during an erection?

Answer 28

→ Vasodilation of the corpus cavernosum | → Partial constriction of the venous return

Question 29

What does the autonomic nervous system do during an erection?

Answer 29

→ Coordinated smooth muscle contraction of the vas deferens, glands and urethra

Question 30

What does the parasympathetic system do during an erection?

Answer 30

→ controls erections

Question 31

What does the sympathetic system do during an erection?

Answer 31

→ Controls the movment of sperm into the epididymis, vas deferens and penile urethra

Question 32

What does the somatic nervous system do during an erection?

Answer 32

→ Expulsion of glandular secretions and evacuation of the urethra

Question 33

How many sperm are produced per day?

Answer 33

→ 300 million

Question 34

What is the normal ejaculate volume?

Answer 34

→ 1.5-6mL

Question 35

What does seminal fluid consist of?

Answer 35

→ Secretions from seminal vesicles → prostate → bulbo-urethral gland and epidydimal fluid

Question 36

What is is the function of the bulbo urethral gland?

Answer 36

→ produces a clear viscous secretion high in salt | → pre-ejaculate

Question 37

What is the function of pre-ejaculate?

Answer 37

→ The fluid lubricates the urethra for the spermatozoa to pass through which neutralizes traces of acidic urine

Question 38

What do seminal vesicle secretions contain?

Answer 38

``` → Proteins → enzymes → fructose → mucus → vitamin C → prostaglandins ```

Question 39

What is the function of the seminal vesicle secretions?

Answer 39

→ provide an energy source | → high pH protects again acidic environment in the vagina

Question 40

What is the function of the prostate?

Answer 40

→ Secretes white fluid roughly 30% of seminal fluid

Question 41

What is the function of the prostatic secretions?

Answer 41

→ High zinc concentration which is anti bacterial | → prostatic acid, phosphatase and prostate specific antigen which are involved in liquefaction

Question 42

What should the normal morpholoy % be?

Answer 42

→ more than 4% normal

Question 43

What does a spermatozoa's head contain?

Answer 43

→ Acrosome

Question 44

What is the acrosome reaction?

Answer 44

→ THe head 'explodes' and enzymes are released which make the sperm bury into the zona pellucida of the egg

Question 45

What do sperm need to undergo for them to be functional?

Answer 45

→ Capacitation

Question 46

When does capacitation need to occur?

Answer 46

→ 4-18 hours of being released

Question 47

What is the mitochondrial sheath for?

Answer 47

→ Swimming

Question 48

What does the axoneme consist of and where is it ?

Answer 48

→ 9 pairs of tubules with a pair down the center | → tail