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Reproduction > Male Infertility > Flashcards

Male Infertility Flashcards

1
Q

which chromosome has the sex determining region?

A

y chromosome

*causes development of testis from bipotential gland

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2
Q

what do the foetal testes secrete?

A

testosterone and mullerian inhibiting factors

*these cause development of male internal genital tract

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3
Q

what are the two primitive genital tracts?

A

wolffian and mullerian ducts

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4
Q

how is the male reproductive tract formed from the two primitive genital tracts?

A

wolffian ducts become repro tract

mullerian ducts degenerate by mullerian inhibiting factor

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5
Q

how is the female reproductive tract formed from the two primitive genital tracts?

A

wolffian ducts degenerate through lack of testosterone

mullerian ducts become repro tract

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6
Q

what hormone causes the differentiation of external genitalia at week 9?

A

dihydrotestosterone

  • present = male
  • absent = female
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7
Q

although external genitalia start to differentiate from 9 weeks, when are you able to recognise it on scan?

A

16 weeks

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8
Q

what is androgen insensitivity syndrome (with karyotype 46XY)?

A

x linked recessive disorder where testes develop but do not descend

androgen induction of wolffian duct does not occur, mullerian inhibition does occur

born phenotypically external genitalia female with absence of uterus and ovaries and short vagina

commonly present at puberty with primary amenorrhoea and lack of pubic hair

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9
Q

what conditions have the possibility to cause reduced penile size?

A

obesity
smoking
environmental
endocrine (testicular failure eg kleinfelters syndrome, crypto-orchidism)

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10
Q

describe the descent of testis and why it is important that this occurs?

A

in utero, testes develop in abdominal cavity and drop into scrotal sac before birth (androgen-dependent)

important due to the lower temperature outside body to facilitate spermatogenesis
*nervous reflexes trigger dartos muscle contraction in scrotal sac to lower/raise testes according to external temperature

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11
Q

what is cryptorchidism?

A

individual has reached adulthood and tests have not descended

reduces sperm count, but if unilateral then usually fertile

  • ochidopexy should be performed below age 14 to minimise risk of testicular germ cell cancer
  • if undescended as adult, consider orchidectomy (risk cancer increase 6x)
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12
Q

what are the functions of the testis?

A

spermatogenesis (seminiferous tubules)

production of testosterone (leydig cells)

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13
Q

where in the spermatozoon contains enzymes for penetrating the ovum?

A

acrosome

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14
Q

what are the roles of sertoli cells within the testes?

A

form a blood-testes barrier (protects sperm from antibody attack and provides suitable fluid composition which allows later stages of development of sperm)
provide nutrients for developing cells
phagocytosis (remove surplus cytoplasm from packaging process and destroy defective cells)
secrete seminiferous tubule fluid (used to carry cells to epididymis)
secrete androgen binding globulin (binds testosterone, essential for sperm production)
secrete inhibin and activin hormones (regulates FSH secretion and control spermtogenesis)

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15
Q

describe the different hormonal controls of spermatogenesis

A

FSH stimulates spermatogenesis together with testosterone
*inhibin decreases secretion of FSH

sertoli cells in seminiferous tubule secretes androgen binding globulin (ABG) and inhibin

LH stimulates testosterone secretion
*testosterone decreases release of GnRH and LH

dihydrotestosterone causes enlargement of male sex organs, secondary sexual characteristics and anabolism

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16
Q

what is the role of gonadotrophin releasing hormone?

A

decapeptide which is released from hypothalamus in bursts every 2-3 hours (begins age 8-12)
stimulates anterior pituitary to produce LH and FSH
under negative feedback control from testosterone

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17
Q

what are the roles of LH and FSH?

A

LH = acts on leydig cells to regulate testosterone secretion

FSH = acts on sertoli cells to enhance spermatogenesis, regulates by negative feedback from inhibin

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18
Q

is production of LH and FSH in males cyclical or non-cyclical?

A

non-cyclical (unlike in females)

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19
Q

what is the role of testosterone?

A

steroid hormone derived from cholesterol produced in leydig cells which is secreted into blood and seminiferous tubules for sperm production

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20
Q

what are the effects of testosterone in the following circumstances:

a) before birth?
b) puberty?
c) adult?

A

a) masculinises reproductive tract and promotes descent of testes
b) promotes puberty and male characteristics (growth and maturation of male repro system)
c) controls spermatogenesis, secondary sexual characteristics, libido, penile erection and aggressive behaviour

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21
Q

what is the role of inhibin and activin?

A

peptides secreted by sertoli cells which act as feedback on FSH (inhibin inhibits and activin stimulates)

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22
Q

what liquifies spermatozoa?

A

enzymes from prostate gland

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23
Q

what is capacitation of spermatozoa?

A

a series of biochemical and electrical events before fertilisation (hyperactive mobility, ability to bind ZP and AR)

24
Q

what is the 6 steps of capacitation of spermatozoa?

A

1) chemoattraction to oocyte and bind to zona pellucida of oocyte
2) docking (specific recognition)
3) acrosomal exocytosis
4) hyperactivated motility
5) penetration and fusion with oocyte membrane
6) zonal reaction

25
Q

where does fertilisation occur?

A

ampullary region of fallopian tube

26
Q

what are the functions of the epididymis and vas deferens?

A

exit route from testes to urethra
concentrate and store sperm
site for sperm maturation

27
Q

what are the functions of seminal vesicles?

A 
produce semen into ejaculatory duct 
supply fructose 
secrete prostaglanding (stimulates motility)
secrete fibrinogen (clot precursor)
28
Q

what are the functions of the prostate gland?

A

produces alkaline fluid (neutralises vaginal acidity)

produces clotting enzymes to clot semen within female

29
Q

what is the function of the bulbourethral glands?

A

secrete mucus to act as lubricant

30
Q

what is the route sperm normally takes?

A

testes -> epididymis -> vas deferens -> ejaculatory duct -> urethra

31
Q

what happens during an erection?

A

blood fills corpora cavernosa (under PS control)

32
Q

what happens during emission?

A

contraction accessory sex glands and vas deferens so semen expelled into urethra

33
Q

what happens during ejaculation?

A

contraction of smooth muscles of urethra and erectile muscles (shoot = sympathetic control)

34
Q

what conditions could cause retrograde ejaculation?

A

neuropathy
prostate surgery
anticholinergic drugs

35
Q

what is the definition of male infertility?

A

infertility resulting from failure of the sperm to normally fertilise the egg
*usually associated with abnormalities in semen analysis

36
Q

male factor infertility is the most common cause of infertility - true or false?

A

true - approx 1/3 of all infertility

37
Q

what is the most common cause of male infertility?

A

idiopathic

38
Q

what are obstructive causes of male infertility?

A

cystic fibrosis
vasectomy
infection

39
Q

what are the non-obstructive causes of male infertility?

A

congenital - cryoptorchadism
infection - mumps orchitis
iatrogenic - chemotherapy / radiotherapy
pathological - testicular tumour
genetic - klinefelters syndrome, microdeletions of Y chromosome, robertsonian translocation
specific semen abnormality - globozoospermia
systemic disorder
endocrine

40
Q

what are the different endocrine causes of male infertility?

A

pituitary tumours - acromegaly, cushings, hyperprolactinaemia

hypothalamic causes - idiopathic, tumours, kallmans syndrome, anorexia

thyroid disorders - hyper or hypothyroidism (decrease sexual function and increase prolactin)

diabetes (decrease sexual function and testosterone)

CAH (increased test)

androgen insensitivity (normal or increased LH and test)

steroid abuse (decrease LH/FSH and test)

41
Q

what should you look for in genital examination of male infertility?

A

testicular volume
presence of vas deferens and epididymis
penis (urethra orifice)
presence of any variocele / other scrotal swelling

42
Q

what are the normal testicular volumes?

A 
pre-pubertal = 1-3mls
adults = 12-25mls
  • if below 5ml unlikely to be fertile
  • measured using orchidometer
43
Q

what is assessed during semen analysis and what are the lower reference limits for these?

A 
volume (mL) = 1.5
density (number) = 39x10^6
motility (what proportion moving) = 40
progression (how well they move) = 32
morphology = 4
44
Q

what factors can affect the result of semen analysis?

A

completeness of sample
period of abstinence eg less than 3 days
condition during transport eg cold
time between production and assessment eg deteriorates if after 1 hour
natural variations between samples
health of man 3 months before production

45
Q

what other further assessments, after semen analysis, can be undertook for male infertility?

A

repeat analysis 6 weeks later
endocrine profile
chromosome analysis
cystic fibrosis screening

depending on results - testicular biopsy, scrotal scan

46
Q

what are the diagnostic features of obstructive infertility?

A

clinical = normal volume, normal secondary sexual characteristics, vas deferens may be absent

endocrine = normal LH, FSH and testosterone

47
Q

what are the diagnostic features of non obstructive infertility?

A

clinical = low testicular volume, reduced secondary sexual characteristics, vas deferens present

endocrine = high LH, FSH +/- low testosterone

48
Q

what assisted conception methods can be used for male infertility?

A 
ICSI
donor insemination (DI)
49
Q

what general advice can be given to men in regards to treatment infertility?

A 
frequent sexual intercourse and avoid lubricants that are toxic to sperm
alcohol <4 units per day 
stop smoking 
BMI <30
avoid tight underwear
certain occupations (overheating and chemicals)
complementary therapies 
anti oxidants (vitamin C or zinc)
50
Q

what is the success rate of a vasectomy reversal?

A

75% if within 3 years
55% after 3 to 8 years
approx 30-40% after 9 to 19 years

51
Q

what medication can be used for hyperprolactinaemia?

A

carbegoline

52
Q

when could psychosexual treatment be useful?

A

in anejaculation conditions

53
Q

what is the indication for surgical sperm aspiration?

A

azoospermia

54
Q

how is surgical sperm aspiration performed and what is the success rate?

A

sperm aspirated surgically (can be done as diagnostic procedure or at time of oocyte recovery)
sperm then injected into oocyte (ICSI)

95% success in obstructed azoospermia and 50% non-obstructive azoospermia

55
Q

what is the indications for donor sperm insemination?

A

azoospermia or very low count
failed ICSI treatment
genetic conditions
infective conditions

56
Q

how is donor sperm insemination carried out and what is success rate?

A

sperm donors matched for recipient characteristics and screened for genetic conditions and STIs
sperm quarantined by cryopreservation and rescreened
prepared thawed semen sample inserted intrauterine at time of ovulation

*15% per treatment cycle

Reproduction (45 decks)

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