Sperm Function Tests Flashcards
Do the seminal vesicles secrete an acidic or alkaline fluid?
Alkaline
Does the prostate gland secrete an acidic or alkaline fluid?
Acid
Describe when you would want to do a vitality test and the different types of vitality tests available
- Used to determine if non motile sperm are alive or dead
- Indicated when sperm motility is less than 40%
- A dye exclusion assay. The live sperm will resist the absorption of certain dyes which will penetrate and stain non viable sperm. Trypan blue and eosin Y are commonly used.
- HOS test. Soerm are placed in hypoosmotic media. Water will enter the cytoplasm and cause the cell, particularly the tail, to swell. This does not damage the sperm and can be used to identify viable sperm for ICSI.
How valuable is the HOS test for sperm vitality?
Limited ability to predict male fertility but HOS of less than 50% is associated with increased miscarriage rates.
What is the clinical reasoning behind sperm antibody testing?
It is thought that anti sperm antibodies may cause agglutination which impedes the sperm passage through cervical mucus, zona binding and fertilisation.
IgA and IgG antibodies are tested for. (IgA are thought to have a greater clinical importance)
They are thought to be caused by an immune response evoked when the blood testis barrier is disrupted
How do you carry out sperm antibody testing?
- Direct Tests
- Mixed agglutination reaction assay (MAR test) on fresh semen
- Immunobead binding assay (IB) on prepared semen. In this study 50% of motile sperm with attached beads is considered to be clinically significant. - Indirect tests (done on seminal plasma, blood, serum, solubilised cervical mucus) Incubate these with antibody free donor sperm and then subject to direct testing.
List some sperm function tests
Post coital test CASA Hemizona and zona pellucida binding Sperm penetration assay Sperm capacitation index Zona free hamster oocyte penetration assay Sperm DNA damage Assessment of reactive oxygen species Sperm proteomics
What are some of the limitations of sperm function testing?
- Lack of standardised method
- Subjective endpoints
- Tests only relevant to a few selected cases
- Inadequate sensitivity and specificity.
- Tests do not appear to help clinical managment
Describe the post coital test and what it is used for?
- Evaluates the interaction of sperm with the cervical mucus and aims to determine that number of active sperm in the mucus and evaluate the survival and behaviour of the sperm.
- Done around the predicted time of ovulation 9 - 14 hours after coitus.
- Over 10 - 20 sperm per 400 high power field is normal. The majority of these sperm demonstrate progressive motility.
In the post coital test what indicates the presence of antisperm antibodies?
Immobilized sperm with side to side shaking motion
What substances are used in vitro to mimic the cervical mucus environment?
Methyly cellulose
Hyaluronic acis
What is the kremer assay and what does it assess?
An in vitro assessment of functional sperm motility.
The sperm are challenged to swim/penetrate a viscous media.
Influx of what is needed in order to initiate hyperactivation?
Ca2+
What is the hemizona binding assay? Who is it useful in?
Used in couples who have failed fertilisation following IVF. Use non fertilised oocytes to assess the ability of the sperm to penetrate the zona.
Why are hamster eggs often used in these sperm function tests?
Removal of the zona pellucida results in loss of all species specificity to egg penetration.
What is the acrosin assay?
AN indirect measure of sperm penetrating capability. It measure acrosin levels which may be responsible for penetration of the zona pellucida and in triggering the acrosome reaction/
What is the sperm chromatin structure assay and what does it test for?
Looks for DNA breaksin sperm DNA
What is the sperm chromatin dispersion test?
“Halosperm” Looks for DNA damage.
Sperm with no damage has a larger halo around it wheras sperm with damagae has no halo.
What are the problems with the sperm tests looking for DNA damage?
- Not clinically approved
- Not consistent or reliable
- No agrreed clinical thresholds
- None are approved or recommened
- Destroy the sperm
What causes oxidative stress in sperm?
When the production of potentially destructive free radicals exceed the natural antioxidant defences.
What is the evidence behind looking for oxidative stress levels in sperm?
- Oxidative stress seen in 30 - 80% of infertile men
2. Oxidative parameters higher in the semen of idiopathic infertile men compared to fertile men
What is the mechanism of action behind oxidative stress and infertility?
- Damage to the sperm membrane causes decreased sperm motility and reduced fertilising ability.
- Causes DNA damage
List some molecular targets implicated in sperm disfunction
Phospholipase c Zeta
Catsper
ADAMs
Izumo
