Sperm Function Tests

Question 1

Do the seminal vesicles secrete an acidic or alkaline fluid?

Answer 1

Alkaline

Question 2

Does the prostate gland secrete an acidic or alkaline fluid?

Answer 2

Acid

Question 3

Describe when you would want to do a vitality test and the different types of vitality tests available

Answer 3

1. Used to determine if non motile sperm are alive or dead
2. Indicated when sperm motility is less than 40%
3. 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.
4. 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.

Question 4

How valuable is the HOS test for sperm vitality?

Answer 4

Limited ability to predict male fertility but HOS of less than 50% is associated with increased miscarriage rates.

Question 5

What is the clinical reasoning behind sperm antibody testing?

Answer 5

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

Question 6

How do you carry out sperm antibody testing?

Answer 6

1. 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.
2. Indirect tests (done on seminal plasma, blood, serum, solubilised cervical mucus) Incubate these with antibody free donor sperm and then subject to direct testing.

Question 7

List some sperm function tests

Answer 7

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

Question 8

What are some of the limitations of sperm function testing?

Answer 8

1. Lack of standardised method
2. Subjective endpoints
3. Tests only relevant to a few selected cases
4. Inadequate sensitivity and specificity.
5. Tests do not appear to help clinical managment

Question 9

Describe the post coital test and what it is used for?

Answer 9

1. 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.
2. Done around the predicted time of ovulation 9 - 14 hours after coitus.
3. Over 10 - 20 sperm per 400 high power field is normal. The majority of these sperm demonstrate progressive motility.

Question 10

In the post coital test what indicates the presence of antisperm antibodies?

Answer 10

Immobilized sperm with side to side shaking motion

Question 11

What substances are used in vitro to mimic the cervical mucus environment?

Answer 11

Methyly cellulose

Hyaluronic acis

Question 12

What is the kremer assay and what does it assess?

Answer 12

An in vitro assessment of functional sperm motility.

The sperm are challenged to swim/penetrate a viscous media.

Question 13

Influx of what is needed in order to initiate hyperactivation?

Answer 13

Ca2+

Question 14

What is the hemizona binding assay? Who is it useful in?

Answer 14

Used in couples who have failed fertilisation following IVF. Use non fertilised oocytes to assess the ability of the sperm to penetrate the zona.

Question 15

Why are hamster eggs often used in these sperm function tests?

Answer 15

Removal of the zona pellucida results in loss of all species specificity to egg penetration.

Question 16

What is the acrosin assay?

Answer 16

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/

Question 17

What is the sperm chromatin structure assay and what does it test for?

Answer 17

Looks for DNA breaksin sperm DNA

Question 18

What is the sperm chromatin dispersion test?

Answer 18

“Halosperm” Looks for DNA damage.

Sperm with no damage has a larger halo around it wheras sperm with damagae has no halo.

Question 19

What are the problems with the sperm tests looking for DNA damage?

Answer 19

1. Not clinically approved
2. Not consistent or reliable
3. No agrreed clinical thresholds
4. None are approved or recommened
5. Destroy the sperm

Question 20

What causes oxidative stress in sperm?

Answer 20

When the production of potentially destructive free radicals exceed the natural antioxidant defences.

Question 21

What is the evidence behind looking for oxidative stress levels in sperm?

Answer 21

1. Oxidative stress seen in 30 - 80% of infertile men

2. Oxidative parameters higher in the semen of idiopathic infertile men compared to fertile men

Question 22

What is the mechanism of action behind oxidative stress and infertility?

Answer 22

1. Damage to the sperm membrane causes decreased sperm motility and reduced fertilising ability.
2. Causes DNA damage

Question 23

List some molecular targets implicated in sperm disfunction

Answer 23

Phospholipase c Zeta
Catsper
ADAMs
Izumo