Spermatogenesis and Male Infertility Flashcards
What determines the development of the internal reproductive tract in the embryo?
SRY on Y chromosome result in the development of testes, and the degeneration of the mullerian ducts
What will the foetal testes secrete?
Testosterone
AMH
What are the 2 primitive genital tracts?
Wolffian
Mullerian
What duct is present in males?
Wolffian
What duct is present in females?
Mullerian
When can you distinguish sex on a USS?
Week 16
What is androgen insensitivity syndrome (testicular feminisation)?
Congenital insensitivity to androgens
Testis develop but do not descend
Androgen induction of wolffian duct does not occur, but mullerian inhibition occurs
What internal sex organs will those with testicular feminisation have?
Externally female genitalia
Absence of uterus and ovaries
Short vagina
How will those with androgen sensitivity present?
Puberty with primary amenorrhoea and a lack of pubic hair
What is the function of the testis?
Spermatogenesis (seminiferous tubules)
Production of testosterone (leydig cells)
What covers the testis?
Double layer of tunical vaginalis
White fibrous tunica albingia
Why is the descent of the testis important?
Lower temp outside body to facilitate spermatogenesis
Nervous reflex triggers dartos muscle contraction in scrotal sac to lower/ raise testes according to the external temp
How common is cryptorchidism?
1:25
When should an orchiopexy be performed in cryptorchidism?
By 12 months due to strong assoc with azoospermia
12 years to minimize risk of testicular germ cell ca
If undescended as adult - consider orchidectomy
What are the venous drainage of the testes?
Left testicular joins left renal
Right drains directly to IVC
What gonadotropin drives sertoli cell function?
FSH
What gonadotropin drives testosterone production?
LH - leydig cells
What is present in the head of a sperm?
Acrosome - enzymes required for penetration of ovum
Nucleus
What is present in the midpiece of the sperm?
Mitochondria
What is present in the tail of the sperm?
Microtubules
What is the function of the sertoli cells?
Blood-testes barrier Nutrientes Phagocytosis Secrete seminiferous tubule fluid Secrete ABG Secretes inhibin and activin
Describe the GnRH release in men?
Every 2-3 hours
Begins age 8-12
What is testosterone?
Steroid hormone derived from cholesterol
Secreted into blood and seminiferous tubules for sperm production
Effect of testosterone before birth?
Masculinises reproductive tract and promotes descent of testes and generation of external genitalia
Role of testosterone in puberty?
Puberty and male characteristics (growth and maturation male reproductive system)
Role of testosterone in the adult?
Spermatogenesis
Secondary sexual characteristics (male body shape, deep voice, thickening of skin), libido, penile erection, aggressive behaviour
What is capacitation?
A series of biochemical and electrical events before fertilisation (hyperactive motility, ability to bind ZP and AR)
How are spermatozoa attracted to oocytes?
Chemoattraction; binds to zona pellucida
What liquefies the spermatozoa?
Enzymes in prostate
Function of the epididymis and vas deferens?
Exit route from testes to urethra
Concentrate and store sperm
Site for sperm maturation
Function of the seminal vesicles?
Produce semen into ejaculatory duct, supply fructose, secrete prostaglandins (motility), secretes fibrinogen (clot precursor)
Function of the prostate gland?
Alkaline fluid (neutralizes vaginal acidity), produces clotting enzymes to clot semen within female
Function of the bulbourethral gland?
Mucus to act as lubricant
What is erection under control from?
Parasymp system
What % of infertility is due to male factor?
30% - biggest portion
What causes obstructive male infertility?
CF - mutation in one gene can result in bilateral absence of vas
Vasectomy
Infection
What causes non-obstructive male infertility?
Cryptorchidism Mumps orchitis Chemo/radiotherapy Testicular tumour Klinefelter's syndrome Globozoospermia Systemic disorder Endocrine
What pituitary tumours can cause male infertility?
ACromegaly
Cushing’s disease
Hyperprolacinaemia
What hypothalamic causes can result in male infertility?
Idiopathic
Tumours
Kallmann syndrome
Anorexia
What are the endocrine causes of male infertility?
Pituitary tumours Hypothalamic Thyroid Diabetes CAH Androgen insensitivity Steroid abuse
How is male infertility assessed?
See as couple Infertility history Andrology history Examination; general and genital Ix; semen analysis
What are the best questions to ask about testosterone?
Facial hair; will be reduced in low testosterone
Early morning erection
What are you examining in a genital male examination?
Testicular volume
Presence of vas and epididymis
Penis; urethral orifice (hypospadia)
Presence of any varicocele or other scrotal swellings
What are the normal testicular volumes?
Pre-pubertal; 1-3mls
Adults; 12-25 mls
How do you measure testicular volume?
Orchidometer
What testicular volume is likely to be infertile?
Less than 5ml
What do you assess in semen analysis?
Volume Density Motility Progression Morphology
What is a normal semen volume?
1.5ml
What is the normal sperm concentration?
15 million sperm per ml
What is normal motility of sperm?
40
What is normal morphology of sperm?
4% morphologically normal
What are factors that can affect semen analysis?
Completeness of sample
Period of abstinence; less than 3 days or over 7 day
Cold condition whilst travelling
Time between production and assessment over 1 hour
Natural variations between samples
Health of man 3 months prior
What are the clinical and endocrine features of obstructive infertility?
Normal testicular volume
Normal secondary sexual characteristics
Vas deferens may be absent
Normal LH, FSH and testosterone
What are the clinical and endocrine features of non-obstructive infertility?
Low testicular vol
Reduced secondary sexual characteristics
Vas deferens present
High LH, FSH +/- low testosterone
What is the treatment of male infertility?
Treat any specific cause e.g. reversal of vasectomy, cabergoline if hyperprolactinemia
ICSI +/- surgical sperm aspiration
Donor insemination
General advice for male infertility?
Frequent sexual inercourse; 2-3x a week Less than 4 units of alcohol per day Stop smoking BMI <30 Avoid tight fitting underwear and prolonged hot baths Certain occupations Complementary therapies Possible benefits of anti-oxidants
Treatment for anejaculation conditions?
Psychosexual treatment
What is ICSI?
Sperm prepared from semen Egg stripped Sperm immobilised Single sperm injected Success rate 35%
What is the indication for surgical sperm aspiration?
Azoospermia
What is surgical sperm aspiration?
Sperm aspirated surgically then injected into oocyte (ICSI_
What are the indications for donor sperm insemination?
Azoospermia or v low count, failed ICSI, genetic conditions, infective conditions
What is the pregnancy rate of donor sperm insemination?
15% per cycle