Male Infertility and Spermatogenesis Flashcards by Kerry Hendrie

What determines our gender?

Chromosomes (XY or XX)
Sex hormones secreted
External + internal genitalia
Psychological factor

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Which chromosome has the sex-defining region?

Y-chromosome

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Which 2 hormones/factors contribute to the development of the internal genital tract in the male?

Testosterone (dihydrotestosterone)

Mullerian inhibiting factor

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There are 2 primitive genital tracts: Wolffian and Mullerian ducts. Which duct contributes to male and female genital tracts respectively?

Males = Wolffian
Females = Mullerian

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Without stimulation by testosterone + Mullerian inhibiting factor, what develops in the male?

Internal genital tract resembling that of a female

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The testes develop in the ________ but descend into the ______ before birth. Why?

Abdominal cavity
Scrotal sac
Lower temperature outside the body facilitates spermatogenesis

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What is cryptorchidism? How is it managed?

Undescended testes, resulting in reduced sperm count and increased risk of testicular cancer
Orchidectomy

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What does testicular descent depend on?

Androgenic drive

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Where does spermatogenesis occur?

Seminiferous tubules

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Where is testosterone secreted from?

Leydig cells

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List the function of Sertoli cells

Form blood-testis barrier (protection)
Provide nutrients for developing cells
Phagocytosis
Secrete seminiferous tubule fluid
Secrete androgen-binding globulin
Regulate FSH levels through inhibin

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Where does LH act in the male?

Leydig cells - regulate testosterone levels

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Where does FSH act in males?

Sertoli cells - enhances spermatogenesis

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What are the 3 main categories of causes of male infertility?

Idiopathic (most common cause)
Obstructive
Non-obstructive

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List some obstructive causes of male infertility

Cystic fibrosis (vas deferens defect)
Vasectomy
Infection

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List some non-obstructive causes of male infertility

Cryptorchidism
Infection
Radiation (chemo/radiotherapy)
Testicular tumour
Genetic (Klinefelter's, microdeletetion of Y ch., robertsonian translocation)
Semen structure abnormality
Systemic/endocrine disorders

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List some pituitary causes of male infertility

Tumours
Acromegaly
Cushing’s disease
Hyperprolactinaemia

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List some hypothalamic causes of male infertility

Tumour
Increased exercise
Kallmann’s syndrome
Anorexia

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Which drug when abused is notorious for causing male infertility?

Steroids

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What would be assessed on genital examination in a male with infertility?

Testicular volume (normal = 12-25ml)
Presence of vas deferens + epidydimis
Penis
Urethral orifice
Presence of swellings/varicocele

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What 5 domains are assessed on semen analysis?

Volume
Density (number of sperm)
Motility (how many are moving)
Progression (how well they move)
Morphology

What extrinsic factors may cause abnormality in semen analysis?

Completeness of sample
Period of abstinence from sex
Conditions during transport e.g. cold
Time delay 
Health of the man

How would testicular volume, secondary sexual characteristics, endocrine hormones and structure of vas deferens be affected in obstructive male infertility?

All normal

Vas deferens may be absent

How would testicular volume, secondary sexual characteristics, endocrine hormones and structure of vas deferens be affected in non-obstructive male infertility?

Low testicular volume
Reduced secondary sexual characteristics
High endocrine hormones
Vas deferens present

List some lifestyle improvements that can help male infertility

``` Frequent sex, 2-3x a week Avoid lubricants (toxic to sperm) Less than 4 units of alcohol a week Stop smoking BMI less than 30 Avoid tight underwear, saunas/hot baths ```

When is ICSI indicated over IUI?

IUI - low sperm count | ICSI - very low sperm count

What is the success (pregnancy) rate of IUI and ICSI?

``` IUI = 15% ICSI = 30% ```

When is surgical sperm aspiration indicated?

Azoospermia (very low sperm count) | when sperm cannot be prepared from semen (ICSI)

What is the success (pregnancy) rate of surgical sperm aspiration?

95% in obstructive | 50% in non-obstructive

If IUI, ICSI and sperm aspiration fail, what is the next option?

Donor sperm

What is androgen insensitivity syndrome? How does it present

Congenital insensitivity to androgens (46XY) causing no androgen induction of wolfian duct (therefore female genitalia) but mullerian inhibition does occur (no uterus/ovaries) Primary amenorrhea and a lack of pubic hair in puberty

Where is sperm stored?

Epididymis

The testis is encased within the...

Tunica vaginalis

List the three sets of erectile tissue within the penis

2 x corpus cavernosum | 1 x corpus spongiosum

How does spermatozoa penetrate the ovum?

Acrosome reaction via the release of enzymes which help to penetrate the egg

What is the action of inhibin in the menstrual cycle?

Reduces secretion of FSH

Why can GnRH not be measured?

It is released in a pulsatile fashion from the hypothalamus

Negative feedback of the hypothalamus and pituitary gland is controlled by...

Testosterone

Production of FSH and LH is cyclical in males and females. True/False?

False | It is non-cyclical in males

List the stages by which spermatozoa undergo to reach the egg

1. Capacitation reactions 2. Chemoattraction to ZP of oocye 3. Acrosome reaction 4. Hyperactivated motility 5. Penetration and fusion with oocyte membrane 6. Zonal reaction

What is the role of the seminal vesicles?

Produce semen into ejaculatory duct

What is the role of the prostate gland in fertilisation?

Alkalises fluid and neutralises vaginal acidity | Produce clotting enzymes to clot semen in the female

What is the role of the bulbourethral gland in fertilisation?

Secrete mucous to act as a lubricant

What is the role of the vas deferens?

Transport sperm from testis to urethra

What is male infertility?

Failure of sperm to normally fertilise egg causing infertility

Male factor is a common cause of infertility. True/ False?

True | 1/3 of infertility problems due to male factor

What would be assessed in a history of a male with infertility?

Duration of infertility, primary or secondary, libido, sexual function, sexual activity PMHx (health of man - DM, respiratory disease, recent illness, GU/testicular infection or inflammation) Surgery or reproductive tract or any treatments FHx (genetic disease) DHx (steroids, antibiotics, alpha blockers, recreational) SHx (environmental exposure to pesticides, heat)

What is the main diagnostic procedure which shows abnormality in male infertility?

Semen analysis

List further investigations that may be indicated in male infertility

``` 6 week repeat semen analysis Endocrine profile Chromosome analysis CF screening Testicular biopsy, scrotal scan ```

List management options for male infertility

General lifestyle advice | Treatment of specific disease e.g. reversal of vasectomy