Male Infertility and Spermatogenesis Flashcards
What determines our gender?
Chromosomes (XY or XX)
Sex hormones secreted
External + internal genitalia
Psychological factor
Which chromosome has the sex-defining region?
Y-chromosome
Which 2 hormones/factors contribute to the development of the internal genital tract in the male?
Testosterone (dihydrotestosterone)
Mullerian inhibiting factor
There are 2 primitive genital tracts: Wolffian and Mullerian ducts. Which duct contributes to male and female genital tracts respectively?
Males = Wolffian Females = Mullerian
Without stimulation by testosterone + Mullerian inhibiting factor, what develops in the male?
Internal genital tract resembling that of a female
The testes develop in the ________ but descend into the ______ before birth. Why?
Abdominal cavity
Scrotal sac
Lower temperature outside the body facilitates spermatogenesis
What is cryptorchidism? How is it managed?
Undescended testes, resulting in reduced sperm count and increased risk of testicular cancer
Orchidectomy
What does testicular descent depend on?
Androgenic drive
Where does spermatogenesis occur?
Seminiferous tubules
Where is testosterone secreted from?
Leydig cells
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
Where does LH act in the male?
Leydig cells - regulate testosterone levels
Where does FSH act in males?
Sertoli cells - enhances spermatogenesis
What are the 3 main categories of causes of male infertility?
Idiopathic (most common cause)
Obstructive
Non-obstructive
List some obstructive causes of male infertility
Cystic fibrosis (vas deferens defect)
Vasectomy
Infection
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
List some pituitary causes of male infertility
Tumours
Acromegaly
Cushing’s disease
Hyperprolactinaemia
List some hypothalamic causes of male infertility
Tumour
Increased exercise
Kallmann’s syndrome
Anorexia
Which drug when abused is notorious for causing male infertility?
Steroids
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
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
- Capacitation reactions
- Chemoattraction to ZP of oocye
- Acrosome reaction
- Hyperactivated motility
- Penetration and fusion with oocyte membrane
- 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
