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Reproduction > Male Infertility > Flashcards

Male Infertility Flashcards

1
Q

What is gender defined as?

A

The socially constructed roles and behaviours that society typically associates with males and females

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2
Q

What are genotype and phenotype determined by?

A

Sex

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3
Q

Where does the key to sexual differentiation lie?

A

In the SRY region of the Y chromosome

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4
Q

Where do primordial germ cells migrate to?

A

Move to gonadal ridge in weeks 5-6 = leads to bipotential gonad

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5
Q

What is the SRY region?

A

Sex determining region of the Y chromosome = causes development of testes from week 7 onwards

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6
Q

How is the SRY region responsible for sexual differentiation?

A

Leydig cells secrete testosterone (converted to dihydrotestosterone)
Sertoli cells secrete mullerian inhibiting factor

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7
Q

What are the two primitive genital tracts?

A

Wolffian and Mullerian tracts

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8
Q

What causes the development of the male internal genital tract?

A

Testosterone and mullerian inhibiting factor

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9
Q

What does an absence of male testicular hormones cause?

A

Development of the female internal genital tract

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10
Q

How does the male internal genital tract develop?

A

Testosterone cause Wolffian ducts to form the epididymis, vas deferens and seminal vesicles
Mullerian ducts degenerate due to mullerian inhibiting factor

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11
Q

How does the female internal genital tract develop?

A

Wolffian ducts degenerate

Mullerian ducts form uterus, fallopian tubes, cervix and upper 1/3 of vagina

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12
Q

What does dihydrotestosterone cause?

A

Stimulates formation of male external genitalia = prostate, penis, scrotum

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13
Q

What occurs in the absence of dihydrotestosterone?

A

Female external genitalia develop = clitoris, labia, vagina

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14
Q

When do external genitalia begin to differentiate?

A

Starts from 9 weeks = recognisable on US from 16 weeks

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15
Q

What is androgen insensitivity syndrome also known as?

A

Testicular feminisation

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16
Q

What is androgen insensitivity syndrome?

A

Congenital insensitivity to testosterone = x-linked recessive, male karotype (46XY), testis develop but don’t descend

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17
Q

What are some features of androgen insensitivity syndrome?

A

No testosterone so induction of Wolffian duct doesn’t occur

Absent uterus and ovaries, but have female external genitalia with short vagina (upper 1/3 absent)

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18
Q

How does androgen insensitivity syndrome present?

A

Present at puberty with primary amenorrhoea and lack of pubic hair

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19
Q

What is the function of the seminiferous tubules?

A

Spermatogenesis

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20
Q

What do the Leydig cells produce?

A

Testosterone

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21
Q

What happens to the testes when in utero?

A

Testes develop in abdominal cavity of foetus

Descend into scrotal sac before birth (androgen dependent)

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22
Q

Why do the testes need to descend to outside of the body?

A

Temperature is lower outside body = allows for production of sperm

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23
Q

What are the muscles involved in lowering/raising the testes in response to temperature?

A

Dartos muscle and cremaster muscle

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24
Q

What are some features of the dartos muscle?

A

Smooth muscle = contraction lowers the testes

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25
Q

What are some features of the cremaster muscle?

A

Skeletal muscle = continuation of internal oblique, contraction raises testes

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26
Q

Do the testes hang at an equal level?

A

No = left testis typically hangs lower than right

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27
Q

What are the testes covered by?

A

Double layer of tunica vaginalis then tunica albuginea and protrudes into testis to create lobules

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28
Q

What is cryptorchidism?

A

Undescended testes = individual has reached adolescence/adulthood and testes haven’t descended

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29
Q

What can cryptorchidism affect?

A

Spermatogenesis = usually fertile if unilateral

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30
Q

When should an orchidopexy be performed on a patient with cryptorchidism?

A

Perform by 12 months due to strong association with infertility or by age 12 to minimise risk of testicular germ cell cancer

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31
Q

What should be done if an adult has undescended testes?

A

Consider orchidectomy

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32
Q

What are the parts of the penis?

A

Base, shaft, glans, foreskin

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33
Q

What are the tissues that make up the penis?

A

Dorsal nerve, blood vessels, connective tissue, erectile tissue

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34
Q

What are the erectile tissues found in the penis?

A

Corpus cavernosum and corpus spongiosum

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35
Q

What are the corpus cavernosum?

A

Two columns of erectile tissue running along sides of the penis = blood fills tissue to cause erection

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36
Q

What is the corpus spongiosum?

A

Column of sponge-like tissue running along the front of the penis and ending at glans = fills with blood during erection to keep urethra open

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37
Q

What are some of the functions of sertoli cells?

A

Form blood-testes barrier
Provide nutrients for developing cells
Phagocytosis
Secrete seminiferous tubule fluid, androgen binding globulin, inhibin and activin

38
Q

What are the functions of the blood-testes barrier?

A

Protects sperm from antibody attack

Provides suitable fluid composition which allows later stages of sperm development

39
Q

Why do sertoli cells carry out phagocytosis?

A

Removes surplus cytoplasm from packaging process and destroys defective cells

40
Q

What is the purpose of seminiferous tubule fluid?

A

Carries cells to the epididymis

41
Q

What is the function of androgen binding globulin?

A

Binds testosterone so concentration stays high in lumen = essential for sperm production

42
Q

What is the function of inhibin and activin?

A

Regulate FSH secretion and control spermatogenesis = inhibin inhibits FSH production and activin promotes FSH secretion

43
Q

What is GnRH?

A

Decapeptide = released from hypothalamus in bursts every 2-3hrs, begins at age 8-12

44
Q

What is the function of GnRH?

A

Stimulates anterior pituitary to produce LH and FSH

Under negative feedback control from testosterone

45
Q

What are gonadotrophins?

A

Glycoproteins secreted by the anterior pituitary = production in males is non-cyclical

46
Q

What are the functions of the gonadotrophins?

A 
LH = acts on Leydig cells, regulates testosterone secretion
FSH = acts on sertoli cells to enhance spermatogenesis , regulated by negative feedback from inhibin
47
Q

What is testosterone?

A

Steroid hormone derived from cholesterol = produced in Leydig cells

48
Q

Where is testosterone secreted?

A

Secreted into blood and seminiferous tubules for sperm production
Exerts negative feedback on hypothalamus and pituitary

49
Q

What are the effects of testosterone before birth?

A

Masculinises reproductive tract and promotes descent of testes

50
Q

What are the effects of testosterone during puberty?

A

Promotes puberty and male characteristics = growth and maturation of male reproductive system

51
Q

What are the effects of testosterone in adults?

A

Controls spermatogenesis, secondary sexual characteristics, libido, penile erection and aggressive behaviour

52
Q

What liquifies spermatozoa?

A

Enzymes from prostate gland

53
Q

What is capacitation?

A

Series of biochemical cellular events before fertilisation

54
Q

What happens to the spermatozoa after ejaculation?

A 
Liquification and capacitation
Chemoattraction to oocyte
Penetration of cumulus complex
Acrosome reaction/zona binding
Fusion with oocyte membrane and fertilisation
55
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

56
Q

What are the functions of the seminal vesicles?

A

Produce semen into ejaculatory duct
Supply fructose
Secrete prostaglandins to stimulate motility
Secrete fibrinogen

57
Q

What are the functions of the prostate gland?

A

Produces alkaline fluid to neutralise vaginal acidity

Produces clotting enzymes to clot semen in female

58
Q

What is the function of the bulbourethral gland?

A

Secrete mucous to act as lubricant

59
Q

What is the route that sperm takes?

A

Testes - epididymis - vas deferens - ejaculatory duct - urethra

60
Q

What occurs in an erection?

A

Blood fills corpus cavernosa = under parasympathetic control

61
Q

What occurs in emission of sperm?

A

Contraction of accessory sex glands and vas deferens so semen is expelled to urethra

62
Q

What occurs in ejaculation?

A

Contraction of smooth muscles of urethra and erectile muscles

63
Q

What is the definition of male infertility?

A

Infertility resulting from failure of sperm to normally fertilise egg

64
Q

What are some features of male infertility?

A

Usually associated with abnormalities in semen analysis

Common = 30% of infertility cases due male factor

65
Q

What is the most common cause of male infertility?

A

Idiopathic = >50% of cases

66
Q

What are the obstructive causes of male infertility?

A

Vasectomy, cystic fibrosis, infection

67
Q

What are the non-obstructive causes of male infertility?

A

Cryptorchidism, mumps orchitis, chemo/radiotherapy, testicular tumour, Klinefelter’s syndrome, microdeletions of Y chromosome, Robertsonian translocation, specific semen abnormality, systemic disease, endocrine cause

68
Q

What are some endocrine causes of non-obstructive male infertility?

A

Idiopathic, tumours, Kallman’s syndrome, anorexia, acromegaly, Cushing’s disease, hyperprolactinaemia, hyper/hypothyroidism, diabetes, congenital adrenal hyperplasia, androgen insensitivity, steroid abuse

69
Q

What do you want to cover in an infertility history?

A

Duration, any treatments tried, libido, sexual function and activity

70
Q

What are important features of a history in a male with infertility?

A

History of STIs, epididymo-orchitis or mumps orchitis
Surgery of reproductive tract = vasectomy
History of testis cancer or undescended testes
Exposure to pesticides or extreme heat

71
Q

What drugs are linked with male infertility?

A

Steroids, sulphasalazine, alpha blockers, 5-alpha-reductase inhibitors, marijuana, excessive alcohol

72
Q

What are you looking for on general examination?

A

Secondary sexual characteristics and presence of gynaecomastia

73
Q

What should be covered in a genital examination?

A

Testicular volume, presence of vas deferens and epididymis, penis and urethral orifice, presence of any scrotal swelling

74
Q

What is the normal testicular volume?

A 
Pre-pubertal = 1-3ml
Adults = 12-25ml
75
Q

How is testicular volume measured?

A

Using orchidometer

76
Q

What testicular volume would indicate infertility?

A

Unlikely to be fertile if below 5ml

77
Q

What parameters are assessed in semen analysis?

A

Volume, density, motility, progressive motility, morphology

78
Q

What are some confounding variables that may affect semen analysis?

A

Completeness of sample
Period of abstinence (e.g <3 days)
Condition during transport (e.g cold)
Time between production and assessment = deterioration if >1hour
Natural variation between samples
Current health and health in prior 2-3 months

79
Q

What are some further assessments that can be done for infertile males?

A

Repeat semen analysis in 2-3 months if abnormal
Endocrine profile = LH, FSH, testosterone, prolactin
Chromosome analysis and cystic fibrosis screening
Testicular biopsy or scrotal scan

80
Q

What are the features of obstructive azoospermia?

A

Normal testicular volume and secondary sexual characteristics
Vas deferens may be absent
Normal LH, FSH and testosterone

81
Q

What are the features of non-obstructive azoospermia?

A

Low testicular volume
Reduced secondary sexual characteristics
Vas deferens present
High LH and FSH +/- low testosterone

82
Q

What general advice would be given to an infertile male?

A

Sexual activity 2-3x per week
Avoid lubricants toxic to sperm
<5 units of alcohol per week and stop smoking
BMI <30 and avoid tight fitting underwear
Prolonged hot baths and saunas may help

83
Q

How successful are reversals of vasectomies?

A

75% success rate if reversed within 3 years

Up to 55% success rate after 3-8 years

84
Q

How is hyperprolactinaemia treated?

A

Cabergoline

85
Q

What may be needed to treat anejaculation?

A

Psychosexual treatment

86
Q

What occurs in intracytoplasmic sperm injection?

A

Sperm prepared from semen or surgical sperm aspirate
Each egg is stripped and sperm is immobilised
Single sperm is injected = 35% success rate

87
Q

What are some surgical methods of sperm retrieval?

A

PESA, TESA, testicular biopsy

88
Q

What is micro-TESA?

A

Specialised microsurgery = high power magnification (12-16x)

89
Q

What occurs in micro-TESA?

A

Microscopic dissection and direct examination of seminiferous tubules to identify regions with spermatogenesis

90
Q

What happens to sperm donors for insemination?

A

Sperm donor is altruistic and not anonymous
Matched for recipient characteristics
Screened for STIs and genetic conditions

91
Q

What are some features of donor insemination?

A

Sperm quarantined by cryopreservation and rescreened

Prepared thawed semen sample inserted intrauterine at time of ovulation

92
Q

How successful is donor insemination?

A

Pregnancy rate = 15% per treatment cycle

Reproduction (62 decks)

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