Male Infertility - Science

Question 1

How is the chromosomal sex of a male established?

Answer 1

An ovum with an X chromosome is fertilised by a sperm with a Y chromosome to form an embryo with XY chromosomes

Question 2

What does a Y chromosome have that an X chromosome does not?

Answer 2

Sex determining region

Question 3

What is the role of the sex determining region of the Y chromosome?

Answer 3

To stimulate the bipotential gonad to differentiate into testes

Question 4

What is male gonadal sex?

Answer 4

The presence of testes

Question 5

What two hormones are secreted by the foetal testes?

Answer 5

Testosterone and Mullerian inhibiting factor

Question 6

What is the role of testosterone secreted by the foetal testes?

Answer 6

Causes undifferentiated external genitalia to develop along male lines i.e. penis and scrotum, and it transforms the Wolffian duct into the male reproductive tract

Question 7

What is the role of Mullerian inhibiting factor secreted by the foetal testes?

Answer 7

Degeneration of the Mullerian ducts

Question 8

What is male genital sex?

Answer 8

The presence of male external genitalia

Question 9

At what point in development do external genitalia start to differentiate? When can the sex be determined on a scan?

Answer 9

9 weeks / 16 weeks

Question 10

In the development of a male embryo, without the stimulus of male testicular hormones, what would happen?

Answer 10

The foetus would develop a female internal genital tract

Question 11

What happens to the Wolffian and Mullerian ducts in the development of a female embryo?

Answer 11

The Wolffian duct degenerates and the Mullerian duct goes on to become the female reproductive tract

Question 12

In terms of embryonic development, what happens in androgen insensitivity syndrome?

Answer 12

Insensitivity to androgens means that the androgen induction of the Wolffian duct does not occur, but Mullerian duct inhibition does occur

Question 13

What would be the karyotype (chromosomal sex) of an individual with androgen insensitivity syndrome?

Answer 13

XY

Question 14

What would be the gonadal sex of an individual with androgen insensitivity syndrome?

Answer 14

They would have developed testes but they would not have descended

Question 15

What would be the genital sex of an individual with androgen insensitivity syndrome?

Answer 15

Phenotypically female external genitalia, but with no uterus/ovaries and a short vagina

Question 16

Individuals with androgen insensitivity syndrome are usually brought up as what gender?

Answer 16

Female

Question 17

How may individuals with androgen insensitivity syndrome present?

Answer 17

At puberty, with a lack of pubic hair and primary amenorrhoea

Question 18

Individuals with diagnosed androgen insensitivity syndrome usually continue life as what gender?

Answer 18

Female

Question 19

How are individuals with androgen insensitivity syndrome treated?

Answer 19

HRT, removal of the undescended testes, and fertility treatment (surrogacy, egg donation) if they want to conceive

Question 20

How is androgen insensitivity syndrome inherited?

Answer 20

X-linked autosomal recessive

Question 21

In utero, where do the testes develop?

Answer 21

In the abdominal cavity of a foetus

Question 22

Where do the testes end up before birth? What is this dependent on?

Answer 22

In the scrotal sac, which is dependent on androgen

Question 23

Why is it important that the testes descend?

Answer 23

Because it is a lower temperature outside the body which is needed to facilitate spermatogenesis

Question 24

Outside the body, what structure is responsible for temperature control of the testes?

Answer 24

Dartos muscle

Question 25

What are the two functions of the testes?

Answer 25

Spermatogenesis and the production of testosterone

Question 26

What structures are responsible for spermatogenesis?

Answer 26

Seminiferous tubules

Question 27

What cells of the testes are responsible for the production of testosterone?

Answer 27

Leydig cells

Question 28

What is cryptorchidism?

Answer 28

The individual has reached adulthood and the testes have not descended

Question 29

What is the advantage of unilateral cryptorchidism?

Answer 29

It maintains fertility

Question 30

Why is it cryptorchidism dangerous?

Answer 30

Increases the risk of testicular germ cell cancer

Question 31

What is the treatment of cryptorchidism if the individual is < 14 years of age?

Answer 31

Orchidoplexy (descending the testes)

Question 32

What is the treatment of cryptorchidism if the individual is an adult?

Answer 32

Orchidectomy

Question 33

How often are LH and FSH secreted in males?

Answer 33

They are secreted constantly

Question 34

When does GnRH start to be released in males? How often is it released?

Answer 34

GnRH release starts at puberty, and from then is secreted in bursts every 2-3 hours

Question 35

What is the role of GnRH?

Answer 35

Stimulates the anterior pituitary gland to secrete LH and FSH

Question 36

GnRH in males is under negative feedback control by what hormone?

Answer 36

Testosterone

Question 37

LH acts on which cells in males?

Answer 37

Leydig cells

Question 38

What is the role of the Leydig cells once LH has acted on them?

Answer 38

Regulate testosterone secretion

Question 39

FSH acts on which cells in males?

Answer 39

Sertoli cells

Question 40

What is the role of the Sertoli cells once FSH has acted on them?

Answer 40

Enhances spermatogenesis

Question 41

FSH is under negative feedback control by what hormone(s)?

Answer 41

Testosterone and inhibin

Question 42

Where is inhibin secreted from?

Answer 42

Sertoli cells

Question 43

LH is under negative feedback control by what hormone(s)?

Answer 43

Testosterone

Question 44

What type of hormone is testosterone?

Answer 44

Steroid hormone

Question 45

Where is testosterone produced?

Answer 45

Leydig cells

Question 46

Where is testosterone secreted into from the Legdig cells?

Answer 46

The blood and seminiferous tubules

Question 47

Testosterone exerts negative feedback on where?

Answer 47

The hypothalamus (GnRH) and anterior pituitary (LH and FSH)

Question 48

What is the role of testosterone at puberty?

Answer 48

Promotion of puberty and development of secondary male characteristics

Question 49

What are the roles of testosterone in an adult?

Answer 49

Controls spermatogenesis, secondary sex characteristics, libido and erection, and may have a role in aggressive behaviour

Question 50

What type of hormones are inhibin and activin?

Answer 50

Peptide hormones

Question 51

Inhibin and activin are secreted by which cells?

Answer 51

Sertoli cells

Question 52

Inhibin and activin exert feedback on which hormone?

Answer 52

FSH

Question 53

After ejaculation, a series of biochemical and electrical events take place before fertilisation. Where does this occur?

Answer 53

Ampulla of the fallopian tube

Question 54

What are the roles of the epididymis and vas deferens?

Answer 54

Exit route from testes to urethra, concentrates and stores sperm, site of sperm maturation

Question 55

What 4 things are secreted by the seminal vesicles?

Answer 55

Seminal fluid, fructose, prostaglandins and fibrinogen

Question 56

What are the roles of the prostate gland?

Answer 56

Produces alkaline fluid to neutralise the vagina and produces clotting enzymes to clot semen within a female

Question 57

What is the role of the bulbourethral gland?

Answer 57

Secretes mucus to act as a lubricant

Question 58

Describe the structures the sperm would pass through from testes to urethra?

Answer 58

Testes, epididymis, vas deferens, ejaculatory duct, urethra

Question 59

When a man is erect, which part of the penis fills with blood?

Answer 59

Corpus cavernosa

Question 60

Erection is under control by which branch of the autonomic nervous system?

Answer 60

Parasympathetic

Question 61

Ejaculation is under control by which branch of the autonomic nervous system?

Answer 61

Sympathetic