L03: Testicular Function

Question 1

What is the definition of a gamete

Answer 1

A mature haploid reproductive cell

Question 2

What is the gamete in males

Answer 2

Sperm

Question 3

What is the gamete in females

Answer 3

Egg

Question 4

Up to what week can you not tell the difference between a male and female

Answer 4

7 weeks

Question 5

What process is occurring during the first 7 weeks

Answer 5

Primordial germ cells arise that give rise to sperm and eggs

Question 6

Which gene on chromosome triggers testis development

Answer 6

SRY gene

Question 7

How can people be genetically male but female

Answer 7

Due to SRY gene mutation or deletion

Question 8

How can people be genetically female but male

Answer 8

Due to translocation of SRY gene

Question 9

After week 7 when there are primordial germ cells what happens to them

Answer 9

They migrate to the gonadal ridges

Question 10

What process occurs in the gonadal ridge when the PGS migrate to it

Answer 10

1) cells form the colemic epithelium penetrate into the medullary mesenchyme
2) this forms the primitive sex cord (that express SRY)
3) PGS then come in
4) primitive secs cords surround the PGCs to form seminiferous tubules
5) migrating ells from mesonephric primordia which from the vasculature of the testis and form leydig cells around the seminiferous tubules

Question 11

When the seminiferous tubules form what are the 2 components of it

Answer 11

1) within the seminiferous tubule:
PCGs are called prospermatogonia
Sex cord cells from Sertoli cells

2) between seminiferous tubules:
Vascularisation occurs by leydig cells

Question 12

When seminiferous tubules form what happens to SRY gene that are expressed by sex cord cells

Answer 12

SRY gene is no longer expressed

Question 13

When seminiferous tubules have formed what 2 hormones are developed

Answer 13

Androgen

Anti mullerian hormone

Question 14

What forms the sperm inside the seminiferous tubules

Answer 14

Primitive germinal cells

Question 15

What structure divides the seminiferous tubules into 2 further sub compartments

Answer 15

Blood testis barrier

Question 16

When does the blood testis barrier form

Answer 16

During puberty PRIOR to spermatogenesis

Question 17

What are the 2 functions of the blood testis barrier

Answer 17

1) separate sperm from the immune system to prevent an immune response
2) selective transport ions and small molecules

Question 18

What are the 3 phases of spermatogenesis

Answer 18

1) proliferation
2) division
3) differentiation

Question 19

Describe what occurs at the proliferation phase starting with prospermatogonia (from PGCs)

Answer 19

1) at puberty the rested prospermatogonia becomes activated and undergoes mitosis at the basal component of the seminiferous tubule
2) reactive prospermatogonia is referred to as As spermatogonia
3) As spermatogonia constantly renew to form A spermagonium
3) A spermatogonium becomes committed to spermatogenesis
4) A spermatogonium undergo mitosis again to form B spermatogonium
5) B spermatogonium divide again to form primary spermatocytes

Question 20

What occurs as the division phase of spermatogenesis

Answer 20

1) primary spermatocytes move to the luminal component of the seminiferous tubule by passing the blood testis barrier
2) primary spermatocytes undergone 1st meiotic division
4) this forms the secondary spermatocytes
5) secondary spermatocytes undergone 2nd meiotic division to form the round spermatids

Question 21

What occurs at the differentiation phase of spermiogeneis

Answer 21

Round spermatids elongate to from elongated spermatids which mature into spermatozoa (sperm)

Question 22

List the key features of a sperm

Answer 22

Acrosome 
Flagellum 
Mitochondria 
Nucleus 
Cytoplasm

Question 23

What does the acrosome contain

Answer 23

Hydrolytic enzymes for acrosome reaction

Question 24

After the acrosome reaction what structure becomes available

Answer 24

Inner acrosomal membrane receptors to fuse with egg

Question 25

What is the flagellum

Answer 25

Tail that allows movement of the sperm

Question 26

What does the mitochondria of the sperm provide

Answer 26

Energy for motility

Question 27

What does the nucleus of the sperm determine

Answer 27

Sex of the embryo (X or Y chromosome)

Question 28

What is the sperm DNA packaged into

Answer 28

Protein called protamines

Question 29

How much cytoplasm does the sperm have

Answer 29

Not much

Question 30

What is spermiation

Answer 30

What the cells are released into the lumen of the seminiferous tubule

Question 31

In humans how long does spermatogenesis take

Answer 31

64 days

Question 32

What does the spermatogenic wave mean

Answer 32

Sperm is constantly produced

Question 33

Apart from sperm what are the other products of the testis

Answer 33

Androgens: mainly testosterone Oestrogens: in small amounts Cytokines: inhibin and AMH

Question 34

Which cell produces testosterone in the testis

Answer 34

Leydig cells

Question 35

What happens to the androgen/testosterone that is produced in the leydig cells

Answer 35

- some are released into the lymph - some are released into the blood - some remain in the seminiferous tubules

Question 36

What happens to the testosterone that remains in the seminiferous tubule

Answer 36

1) Testesterone is converted to dihydrotestosterone (DHT) in Sertoli cells (within the seminiferous tubule) as they express the enzyme 5-alpha Reductase for the conversion 2) some of this then binds to androgen receptors in Sertoli cells to drive spermatogenesis 3) some of this binds to androgen binding protein that remain in the testis

Question 37

Which cell in the testis produced inhibin

Answer 37

Sertoli cells

Question 38

When inhibin is produced by Sertoli cells what is the role of inhibin

Answer 38

Supress the anterior pituitary gland to decrease FSH production

Question 39

Which cell in the testis produced AMH

Answer 39

Sertoli cells

Question 40

What role does AMH have when it is produced

Answer 40

Embryonic role in reproductive system

Question 41

Describe the HPG axis in puberty

Answer 41

1) hypothalamus secrets GNRH to the anterior pituitary gland 2) anterior pituitary gland produces and releases LH/FHS 3) LH binds to LHCGR on leydig cells 4) leydig cells produce testosterone which move to the seminiferous tubules to become converted to dihydrotestosterone via Sertoli cells 5) some bind to androgen receptor on Sertoli cells for stimulation of spermatogenesis 6) FSH that is released binds to FSHR on Sertoli cells 7) this causes Sertoli cells to increase androgen receptor to increase sensitivity to testosterone production by leydig cells 8) Sertoli cells also stimulate the prouction of inhibin which supress the HPG axis.

Question 42

When spermatozoa is made in the testis are they mature

Answer 42

No

Question 43

How does the spermatozoa mature

Answer 43

When they are released in the lumen and undergone maturation in the male tract

Question 44

When sperm is released in the lumen of the testis where does it enter

Answer 44

Rete testis

Question 45

After the rete testis where does the sperm go

Answer 45

Epididymis

Question 46

What occurs at the epididymis for the sperm to mature

Answer 46

Epididymis provided molecules for sperm to acquire fertility and maturity

Question 47

What are the 3 regions the epididymis is split into

Answer 47

Head Body Tail

Question 48

After the epididymis where does the sperm pass into

Answer 48

Vas deferens

Question 49

What is the vas deferens for sperm

Answer 49

Storage reservoir

Question 50

At ejaculation what is released

Answer 50

Sperm | Seminal plasma

Question 51

Where does the seminal plasma come from

Answer 51

Accessory sex glands

Question 52

What is the seminal plasma involve

Answer 52

Fructose Buffer Anti-oxidants

Question 53

What are the 2 main accessory glands

Answer 53

Seminal vesicle | Prostate

Question 54

Where does the seminal vesicles empty into during ejaculation

Answer 54

Ejaculatory duct

Question 55

What does the seminal vesicles secret to stop ejaculate clotting

Answer 55

Fibrinogen like substrate

Question 56

What does the prostate secrete

Answer 56

Fluid that is alkaline high in zinc

Question 57

What does the alkaline high in zinc protect the sperm from

Answer 57

Acidic environment

Question 58

What else does the prostate secrete

Answer 58

Ejaculate clotting enzymes And Enzymes that cause liquefaction (so the sperm doesn’t stay in the vagina forever)

Question 59

At what phase does the prostate secrete

Answer 59

Capulation

Question 60

What does the bulbo-urethral gland produce

Answer 60

The pre-ejaculate

Question 61

Why is a pre-ejaculate secrete into the urethra

Answer 61

For lubrication and neutralisation for acidic urine in the urethra before ejaculation

Question 62

Where does capacitation of the sperm occur

Answer 62

In the vagina

Question 63

What are the 2 components of capacitation

Answer 63

1) Change in sperm motility- hypermotility of the sperm to allow it into the cervix 2) acrosome reaction when the sperm gets to the egg