Male Infertility Flashcards
What do fetal testes secrete?
Testosterone and Mullerian inhibiting factors
What are the two primitive genital tracts?
Wolffian and Mullerian ducts
In males, which duct degenerates, Wolffian or Mullerian?
Mullerian
The wolffian becomes the repro tract
What occurs if no male testicular hormones are present?
Fetus will develop female internal genital tract
In females, which duct degenerates, Wolffian or Mullerian?
Wolffian
The Mullerian becomes the repro tract
What is Androgen Insensitivity syndrome? (Testicular feminisation)
Congenital insensitivity to androgens
X-linked karyotype (46XY)
Testes develop but don’t descend
What happens in Androgen Insensitivity syndrome?
Androgen induction of wolffian inhibition does not occur, Mullerian inhibition does occur
born phenotypically external geneitalia female, absence of a uterus and ovaries with short vagina
When does Androgen Insensitivity syndrome commonly present?
At puberty with primary amenorrhoea, lack of pubic hair
How do the testes descend?
In utero, testes develop in abdominal cavity of foetus and drop into scrotal sac before birth (androgen dependant)
Why is it important that the testes descend?
Lower temperature outside the body to facilitate spermatogenesis
How do the testes raise and lower according to external temperature?
Nervous reflexes trigger dartos muscle contraction in scrotal sac
What is Cryptorchidism?
Undescended testes
What are the clinical implications of Cryptorchidism?
Reduced sperm count, if unilateral usually infertile
What procedure helps to reduce risk of testicular germ cell cancer?
Orchidopexy (done before age 14 years
If testes are undescended as an adult, what procedure should be considered and why?
Orchidectomy because cancer risk is X6
Where does spermatogenesis occur?
Seminiferous tubules
Where is testosterone produced?
Leydig cells
What part of the sperm contains enzymes for penetrating the ovum?
The acrosome
Why does the sperm have many mitochondria?
To power the tail
What is a spermatozoon?
A sperm cell
What is present in the tail?
Microtubules
What are the 6 roles of Sertoli cells?
Forms a blood-testes barrier Provides nutrients Phagocytosis Secrete seminiferous tubule fluid Secrete androgen binding globulin Secrete inhibin and activin hormones
What can a lack of testosterone lead to?
Osteoporosis
Why is a blood-sperm barrier important?
Protects sperm from antibody attack
Provides suitable fluid composition which allows later stages of sperm development
Where are cells carried to via the seminiferous tubule fluid?
Epididymis
What does androgen binding globulin do?
Binds testosterone so concentration remains high in lumen
Essential for sperm production
What inhibin and activin hormones are secreted?
FSH secretion is regulated and controls spermatogenesis
What does dihydrotestosterone cause?
Enlargement of male sex organs
Secondary sexual characteristics
Anabolism
What does testosterone decrease the release of?
GnRH and LH
What stimulates the testosterone secretion?
LH
What stimulates spermatogenesis?
Testosterone and FSH
Describe Gonadotrophin Releasing Hormone
Decapeptide
Released from hypothalamus in bursts every 2-3 hours (begins age 8-12 years)
What does Gonadotrophin Releasing Hormone stimulate?
Anterior pituitary to produce LH and FSH
What controls Gonadotrophin Releasing Hormone via negative feedback?
testosterone
What does LH act upon?
Leydig cells
What does FSH act upon?
Sertoli cells
How is FSH and LH different in males compared to females?
Non-cyclical in males
Describe testosterone
Produced in Leydig cells
Steroid hormones derived from cholesterol
Secreted into blood and seminiferous tubules for sperm production
Negative feedback on hypothalamus and pituitary gland
What are the effects of testosterone before birth?
Masculinises reproductive tract and promotes descent of testes
What are the effects of testosterone during puberty?
Promotes puberty and male characteristics (growth and maturation male repro system)
What is the effect of testosterone in an adult?
Controls spermatogenesis, secondary sexual characteristics (male body shape, deep voice, thickens skin), libido, erection, aggressive behaviour
What is inhibin and activin?
peptides
Secreted by Sertoli cells
Feedback on FSH
What does inhibin descrease secretion of?
FSH
What happens to spermatozoa after ejaculation?
Liquified by enzymes from prostate gland
What does the spermatozoa have a chemoattraction to?
Oocyte and bind to zona pellucida of oocyte
What is the function of the epididymis and vas deferens?
Exit route from testes to urethra, concentrate and sperm storage.
site for sperm maturation
What is the function of the seminal vesicles?
Produce semen into ejaculatory duct, supply fructose, secrete prostaglandins (stimulate motility), secrete fibrinogens (clot precursor)
What are the functions of the prostate gland?
Produces alkaline fluid (neutralises vaginal acidity), produces clotting enzymes to clot semen within female
What is the function of the Bulbourethral glands?
Secrete mucus to act as lubricant
What is the route of sperm?
testes - epididymis - vas deferens - ejaculatory duct - urethra
What pathway controls ejaculation?
Sympathetic control
What is the most common cause of male infertility?
Idiopathic
What are the obstructive causes of male infertility?
Cystic fibrosis
vasectomy
Infection
What are the congenital and infectuous causes of male infertility?
C - Cryptorchadism
I - Mumps, orchitis
What are the latrogenic and pathological causes of male infertility?
I - Chemo/radio therapy
P - Testicular tumour
What are the genetic causes of male infertility?
Kleinfelters
Microdeletions of Y chromosome
Robertsonian translocation
What is the specific semen abnormality?
Globozoospermia
What are the pituitary causes of male infertility?
Acromegaly
Cushings
Hyperprolapctinaemia
Decreased LH, FSH and testosterone
What are the hypothalmic causes of male infertility?
Idiopathic tumours
Kallman’s
Anorexia
decreased LH, FSH and testosterone
What are the Thyroid causes of male infertility?
Hyper/hypo
What other endocrine disorders can cause male infertility?
Diabetes
CAH
Androgen insensitivity
Steroid abuse
How do you examine male infertility?
Look for gynaecomastia and secondary sexual characteristics testicular volume Vas deferens and epididymis present Penis Varicocele etc
What is the normal testicular volume?
Pre-pubertal 1-3mls
Adulrts 12-25mls
If below 5mls then unlikely to be fertile
How do you measure testicular volume?
Orchidometer
What do you measure with a semen sample?
Volume Density Motility Progression Morphology
How long prior to ejaculation should a mans health be considered?
3 months
What are the further assessments for semen analysis?
Repeat 6 weeks later
Endocrine profile (LH, FSH, testosterone, PRL, TSH)
Chromosome analysis
Cystic fibrosis screening
Depending on results - testicular biopsy, scrotal scan
How do you treat male infertility?
Frequency of sexual characteristics Alcohol < 4 units per day No smoking BMI <30 avoid tight underwear Antioxidants (Vit C or zinc)
What is Intra-uterine Insemination?
Indication of mildly low sperm count
Semen prepared to produce concentrated sperm sample
Inseminated into uterine cavity around time of ovulation
15% pregnancy rate
What is Intracytoplasmic sperm injection?
Indications are very low sperm count
Procedure is sperm injected into stripped oocyte obtained during IVF
Pregnancy rate is 30% per cycle
What is surgical sperm aspiration?
Indication is azoospermia
Sperm aspirated surgically
Sperm injected into oocyte
95% in azoospermia and 50% in non-obstructive azoospermia
What is donor sperm insemination?
Azzospermia or very low count, genetic conditions or infective conditions
Sperm donors matched for recipient characteristics and screened for genetic diseases and STI’s
Sperm quarantined by cryopreservation and rescreened
Prepared thawed semen sample inserted into intrauterine at time of ovulation
15% success rate
