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Male Infertility Flashcards

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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
What are some features of the cremaster muscle?
Skeletal muscle = continuation of internal oblique, contraction raises testes
26
Do the testes hang at an equal level?
No = left testis typically hangs lower than right
27
What are the testes covered by?
Double layer of tunica vaginalis then tunica albuginea and protrudes into testis to create lobules
28
What is cryptorchidism?
Undescended testes = individual has reached adolescence/adulthood and testes haven't descended
29
What can cryptorchidism affect?
Spermatogenesis = usually fertile if unilateral
30
When should an orchidopexy be performed on a patient with cryptorchidism?
Perform by 12 months due to strong association with infertility or by age 12 to minimise risk of testicular germ cell cancer
31
What should be done if an adult has undescended testes?
Consider orchidectomy
32
What are the parts of the penis?
Base, shaft, glans, foreskin
33
What are the tissues that make up the penis?
Dorsal nerve, blood vessels, connective tissue, erectile tissue
34
What are the erectile tissues found in the penis?
Corpus cavernosum and corpus spongiosum
35
What are the corpus cavernosum?
Two columns of erectile tissue running along sides of the penis = blood fills tissue to cause erection
36
What is the corpus spongiosum?
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
37
What are some of the functions of sertoli cells?
Form blood-testes barrier Provide nutrients for developing cells Phagocytosis Secrete seminiferous tubule fluid, androgen binding globulin, inhibin and activin
38
What are the functions of the blood-testes barrier?
Protects sperm from antibody attack | Provides suitable fluid composition which allows later stages of sperm development
39
Why do sertoli cells carry out phagocytosis?
Removes surplus cytoplasm from packaging process and destroys defective cells
40
What is the purpose of seminiferous tubule fluid?
Carries cells to the epididymis
41
What is the function of androgen binding globulin?
Binds testosterone so concentration stays high in lumen = essential for sperm production
42
What is the function of inhibin and activin?
Regulate FSH secretion and control spermatogenesis = inhibin inhibits FSH production and activin promotes FSH secretion
43
What is GnRH?
Decapeptide = released from hypothalamus in bursts every 2-3hrs, begins at age 8-12
44
What is the function of GnRH?
Stimulates anterior pituitary to produce LH and FSH | Under negative feedback control from testosterone
45
What are gonadotrophins?
Glycoproteins secreted by the anterior pituitary = production in males is non-cyclical
46
What are the functions of the gonadotrophins?
``` LH = acts on Leydig cells, regulates testosterone secretion FSH = acts on sertoli cells to enhance spermatogenesis , regulated by negative feedback from inhibin ```
47
What is testosterone?
Steroid hormone derived from cholesterol = produced in Leydig cells
48
Where is testosterone secreted?
Secreted into blood and seminiferous tubules for sperm production Exerts negative feedback on hypothalamus and pituitary
49
What are the effects of testosterone before birth?
Masculinises reproductive tract and promotes descent of testes
50
What are the effects of testosterone during puberty?
Promotes puberty and male characteristics = growth and maturation of male reproductive system
51
What are the effects of testosterone in adults?
Controls spermatogenesis, secondary sexual characteristics, libido, penile erection and aggressive behaviour
52
What liquifies spermatozoa?
Enzymes from prostate gland
53
What is capacitation?
Series of biochemical cellular events before fertilisation
54
What happens to the spermatozoa after ejaculation?
``` Liquification and capacitation Chemoattraction to oocyte Penetration of cumulus complex Acrosome reaction/zona binding Fusion with oocyte membrane and fertilisation ```
55
What are the functions of the epididymis and vas deferens?
Exit route from testes to urethra Concentrate and store sperm Site for sperm maturation
56
What are the functions of the seminal vesicles?
Produce semen into ejaculatory duct Supply fructose Secrete prostaglandins to stimulate motility Secrete fibrinogen
57
What are the functions of the prostate gland?
Produces alkaline fluid to neutralise vaginal acidity | Produces clotting enzymes to clot semen in female
58
What is the function of the bulbourethral gland?
Secrete mucous to act as lubricant
59
What is the route that sperm takes?
Testes - epididymis - vas deferens - ejaculatory duct - urethra
60
What occurs in an erection?
Blood fills corpus cavernosa = under parasympathetic control
61
What occurs in emission of sperm?
Contraction of accessory sex glands and vas deferens so semen is expelled to urethra
62
What occurs in ejaculation?
Contraction of smooth muscles of urethra and erectile muscles
63
What is the definition of male infertility?
Infertility resulting from failure of sperm to normally fertilise egg
64
What are some features of male infertility?
Usually associated with abnormalities in semen analysis | Common = 30% of infertility cases due male factor
65
What is the most common cause of male infertility?
Idiopathic = >50% of cases
66
What are the obstructive causes of male infertility?
Vasectomy, cystic fibrosis, infection
67
What are the non-obstructive causes of male infertility?
Cryptorchidism, mumps orchitis, chemo/radiotherapy, testicular tumour, Klinefelter's syndrome, microdeletions of Y chromosome, Robertsonian translocation, specific semen abnormality, systemic disease, endocrine cause
68
What are some endocrine causes of non-obstructive male infertility?
Idiopathic, tumours, Kallman's syndrome, anorexia, acromegaly, Cushing's disease, hyperprolactinaemia, hyper/hypothyroidism, diabetes, congenital adrenal hyperplasia, androgen insensitivity, steroid abuse
69
What do you want to cover in an infertility history?
Duration, any treatments tried, libido, sexual function and activity
70
What are important features of a history in a male with infertility?
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
What drugs are linked with male infertility?
Steroids, sulphasalazine, alpha blockers, 5-alpha-reductase inhibitors, marijuana, excessive alcohol
72
What are you looking for on general examination?
Secondary sexual characteristics and presence of gynaecomastia
73
What should be covered in a genital examination?
Testicular volume, presence of vas deferens and epididymis, penis and urethral orifice, presence of any scrotal swelling
74
What is the normal testicular volume?
``` Pre-pubertal = 1-3ml Adults = 12-25ml ```
75
How is testicular volume measured?
Using orchidometer
76
What testicular volume would indicate infertility?
Unlikely to be fertile if below 5ml
77
What parameters are assessed in semen analysis?
Volume, density, motility, progressive motility, morphology
78
What are some confounding variables that may affect semen analysis?
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
What are some further assessments that can be done for infertile males?
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
What are the features of obstructive azoospermia?
Normal testicular volume and secondary sexual characteristics Vas deferens may be absent Normal LH, FSH and testosterone
81
What are the features of non-obstructive azoospermia?
Low testicular volume Reduced secondary sexual characteristics Vas deferens present High LH and FSH +/- low testosterone
82
What general advice would be given to an infertile male?
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
How successful are reversals of vasectomies?
75% success rate if reversed within 3 years | Up to 55% success rate after 3-8 years
84
How is hyperprolactinaemia treated?
Cabergoline
85
What may be needed to treat anejaculation?
Psychosexual treatment
86
What occurs in intracytoplasmic sperm injection?
Sperm prepared from semen or surgical sperm aspirate Each egg is stripped and sperm is immobilised Single sperm is injected = 35% success rate
87
What are some surgical methods of sperm retrieval?
PESA, TESA, testicular biopsy
88
What is micro-TESA?
Specialised microsurgery = high power magnification (12-16x)
89
What occurs in micro-TESA?
Microscopic dissection and direct examination of seminiferous tubules to identify regions with spermatogenesis
90
What happens to sperm donors for insemination?
Sperm donor is altruistic and not anonymous Matched for recipient characteristics Screened for STIs and genetic conditions
91
What are some features of donor insemination?
Sperm quarantined by cryopreservation and rescreened | Prepared thawed semen sample inserted intrauterine at time of ovulation
92
How successful is donor insemination?
Pregnancy rate = 15% per treatment cycle

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