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Repro and Sexual Health > Spermatogenesis and Male Infertility > Flashcards

Spermatogenesis and Male Infertility Flashcards

1
Q

when do primordial germ cells migrate to gonadal ridge?

A

week 5-6

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2
Q

what does Y chromosome cause?

A

development of testis at week 7
leydig cells secrete testosterone (will become DHT)
sertoli cells secrete mullerian inhibiting factor

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3
Q

ducts in males?

A

wolffian = becomes reproductive tract (epididymis, vas defrens, seminal vesicles)
mullerian duct = degenerates

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4
Q

ducts in females?

A

opposite

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5
Q

what does DHT stimulate?

A

development of male external genitalia

female genitalia develops in its absence

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6
Q

when can gender be differentiated on a scan?

A

week 16

starts to differentiate at wek 9

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7
Q

what is androgen insensitivity syndrome?

A

X linked congenital insensitivity to androgens

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8
Q

features of androgen insensitivity syndrome?

A

testes develop but dont descend
androgen induction of wolffian duct does not occur and mullerian inhibition does occur
causes phenotypically female external genitalia but without uterus or ovaries and a short vagina
often presents are puberty with primary amenorrhoea and lack of pubic hair

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9
Q

cells of the smeiniferous tubules?

A

sertoli cells

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10
Q

which cells produce sperm?

A

seroli sperm

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11
Q

descent of testes in utero?

A

testes develop in abdomen on foetus
descend into scrotal sac before birth (androgen dependent)
- etsticukar artery is branch of aorta
- veins in similar path (L testicular vein joins L renal vein, R drains straight into IVC)
- lymphatic drainage to abdomen

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12
Q

why must the testes descend?

A

need lower temp for spermatogenesis

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13
Q

what muscle controls lifting/descent of testes?

A

dartos muscle

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14
Q

what is cryptorchidism?

A

undescended testes
individual has reached adolescence/adulthood and testes have not descended
(usually descend by 6-9 months)

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15
Q

implications of chryptorchidism?

A

affects spermatogenesis (low sperm output)
germ cell cancer risk
- orchidopexy before age 14 can reduce risk
- or orchidectomy if adult

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16
Q

what does the urethra pass through in the penis?

A

corpus spongiosum

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17
Q

what causes an erection?

A

blood engorging in corpus cavernosum and corpus spongiosum

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18
Q

what hormone drives sertoli function and therefore sperm production?

A

FSH

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19
Q

where is genetic info held in sperm?

A

head

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20
Q

what else is contained within the sperm cell?

A

acrosome covers head (contains enzymes for penetrating ovum)

mitochondria in midpiece

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21
Q

6 functions of sertoli cells?

A

form blood-testes barrier (protects sperm from antibody attack)
provide nutrients for developing cells
phagocytosis (surplus cytoplasm and defective cells)
secrete seminiferous tubule fluid (carries cells to epididymis)
secrete androgen binding globulin (binds to testosterone to maintain high levels)
secrete inhibin and activin hormones (regulates FSH and controls spermatogenesis)

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22
Q

what does LH affect?

A

leydig cells

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23
Q

function of inhibin?

A

decreases secretion of FSH

FSH stimulates spermatogenesis so therefore causes low sperm

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24
Q

describe gonadotrophin releasing hormone?

A

decapeptide released from hypothalamus in bursts every 2-3 hours
stimulates anterior pituitary to produce LH and FSH
under negative feedback control from testosterone

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25
Q

what are gonadotrophins?

A

glycoproteins secreted by anterior pituitary
LH - acts on leydig cells to regulate testosterone
FSH - acts on sertoli cells to enhance spermatogenesis, regulates by negative feedback from inhibin

26
Q

what produces testosterone?

A

leydig cells

27
Q

what type of hormone is testosterone?

A

steroid derived from choelsterol

28
Q

effects of testosterone?

A

negative feedback on anterior pituitary
before birth:
- masculine reproductive tract and promotes descent of testes
puberty:
- promotes puberty and male characteristics (growth and maturation male reproductive system)
adult:
- controls spermatogenesis, secondary sexual characteristics, libido, penile erection, aggressive behaviour

29
Q

what are inhibin and activin?

A

peptides secreted by sertoli cells
feedback on FSH
- inhibin inhibits and activin stimulates

30
Q

what happens to spermatozoa after ejaculation?

A

liquefied by enzymes from prostate gland
capacitation:
- series of biochemical cellular events before fertilization (hyperactivated motility, ability to bind to ZP and AR of egg)
chemoattraction to oocyte
penetration of cumulus complex
acrosome reaction/zona binding
fusion with oocyte membrane and fertilization

31
Q

where does fertilization occur?

A

ampulla of fallopian tube

32
Q

function of epididymis and vas deferens?

A

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

33
Q

function of seminal veisicles?

A

produce semen into ejaculatory duct, supply fructose, secrete prostaglandins (stimulate motility) and secrete fibrinogen (clos precursor)

34
Q

function of prostate?

A

produces alkaline fluid which neutralizes vaginal acidity

produces clotting enzymes to clot semen within female

35
Q

function of bulbourethral glands?

A

secrete mucous to act as lubricant

36
Q

general function of accessory glands?

A

secrete semen to suspend and sustain sperm

37
Q

route of sperm?

A

testes > epididymis > vas deferens > ejaculatory duct > urethra

38
Q

what causes erection?

A

blood fills corpora cavernosa (under parasympathetic control)

39
Q

what causes emission?

A

contraction accessory sex glands and was deferens so semen expelled to urethra

40
Q

what causes ejaculation?

A

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

41
Q

definition of male infertility?

A

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

42
Q

most common cause of male infertility?

A

idiopathic

43
Q

obstructive causes of male infertility?

A

CF
vasectomy
infection

44
Q

non-obstructive causes of male infertility?

A 
congenital (e.g cryptorchadism)
infection (e.g mumps)
iatrogenic (chemo)
pathology (testicular tumour)
genetic (chromosomal e.g kleinfelter's)
specific semen abnormality (e.g globozoospermia)
systemic disorder
endocrine
45
Q

endocrine causes of male nfertility?

A

hypothalamus (idiopathic, tumour, kallman’s, anorexia)
pituitary tumours (acromegaly, cushings, hyperprolactinaemia)
thyroid (hyper/hypo)
diabetes
CAH (increases testosterone)
androgen insensitivity
steroid abuse (decerases testosterone and LH/FSH)

46
Q

questions to determine testosterone levels?

A

feeling tired
needing to shave less
loss of libido
loss of early morning erection

47
Q

examination in male infertility?

A

general (look for 2ndary sexual characteristics and gynaecomastia etc)
genital
- testicle volume
- presence of vas deferens and epididymis
- penis and urethral orifice
- presence of any variocele/other scrotal swelling

48
Q

normal testicular volume?

A

pre-puberty = 1-3 mls
adult = 12-25 mls
unlikely to be fertile if under 5ml

49
Q

how is testicular volume measured?

A

orchidometer

50
Q

what is measured in semen analysis?

A 
volume
density (numbers of sperm)
motility (how many moving)
progression (how they move)
morphology
51
Q

what factors can influence result of semen analysis?

A

completeness of sample
period of abstinence (must be at least 2 days but no more than 7)
condition during transport (e.g too cold)
time between production and assessment (must be <1 hr)
natural variants between samples
health of man 3 months before production

52
Q

further assessment in male infertility?

A

repeat semen analysis after 6 weeks
endocrine profile (LH, FSH, testosterone, PRL, TSH)
chromosome analysis
CF screen
depending on results - testicular biopsy, scrotal scan

53
Q

clinical features of obstructive male infertility?

A

normal testicular volume
normal 2ndary sexual characteristics
vas deferens may be absent
normal LH, FSH and testosterone

54
Q

clinical features of non-obstructive male infertility?

A

low testicular volume
reduced 2ndary sexual characteristics
vsa deferens present
high LH, FSH +/- low testosterone

55
Q

general advice in male infertility?

A

frequent intercourse (2-3 times per week and avoid toxic lubricants)
<4 units alcohol per week
stop smoking
BMI <30
avoid tight fitting underwear and prolonged heat/hot water exposure
certain occupations (exposure to heat/chemicals etc)
complementary therapies and possible benefits of anti-oxidants etc

56
Q

treatment of specific disorders in male infertility?

A 
reversal of vasectomy (works best if done within 3 years and more worth it if female is young)
endocrine (e.g cabergoline for hyperprolactinaemia)
anejaculation conditions (e.g psychosexual treatment)
chronic disorders (e.g renal failure)
medications (steroids, immunotherapy etc)
57
Q

IVF vs ICSI?

A 
IVF = normal sperm used
ICSI = sperm is abnormal so injected manually into the egg
58
Q

methods of sperm retrieval?

A

PESA
TESA
testicular biopsy

59
Q

normal testicular volume?

A

12-25mls

60
Q

indications for donor sperm insemination?

A 
azzospermia
very low count
failed ISCI
genetic conditions
infective conditions

Repro and Sexual Health (63 decks)

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