Sperm Motility And Vitality Flashcards
How do sperm get their energy?
Sperm is basically packaged DNA with an onboard motor.
Most evidence points to aerobic respiration as the principle method of energy production including oxidative phosphorylation and the mitochondrial production of ATP.
Mitochondria are found only in the mid piece of the sperm.
There is some evidence that fructolysis (respiration of fructose within seminal plasma) also occurs in the sperm. Thus glycolysis (fructolysis) appears to be responsible for some of the energy provision of the sperm.
Describe activated motility in sperm.
Activated motility is the low amplitude beating of the flagellum. It is a linear and rapid motion.
Activated motility is seen in sperm stored in the epididymis, the semen, in sperm swimming in cervical mucus and in sperm spears toons for assisted conception procedures.
Describe Hyperactivated motility in sperm.
Later in the life of the sperm they switch to Hyperactivated motility.
Hyperactivated motility involves flagellar beatings resulting in circular or star/spin motions. In between those characteristic motions we get a transition phase where the sperm are dormant for a second or two and then we get a phase when it can switch to a more linear progression. However, if you observe the sperm long enough it can change back to circular and star/spin motion.
Hyperactivated motility is associated with capacitation. We characteristically see this kind of motility in the Fallopian tubes, particularly at the site of fertilisation. It is also seen in sperm that are incubated for long periods of time out of the cervical plasma and within a particular wash media that may be used to culture sperm during assisted conception.
What important process is Hyperactivated motility thought to be associated with? Describe this associated process.
Hyperactivated motility is thought to be associated with capacitation. Capacitation is the process by which the sperm acquires its fertilising capacity. Capacitation is chemically characterised by a huge calcium influx, changes in the lipid membrane fluidity and lipid redistribution.
What were the four WHO categories for grading sperm motility pre-2010?
A). Rapid progressive (more than or equal to 25um per second at 37C).
B). Slow or sluggish progressive (between 5 and 24um/sec).
C). Non progressive (less than 5um/second).
D). Immotile.
Why do we bother grading sperm motility?
Reporting sample overall motility is misleading and gives no indication of the relative energy and fertility potential of the sperm.
A number of studies have demonstrated that the extent of sperm motility is important and the overall velocity of the sample is the most important aspect of motility in relation to pregnancy rates.
Why did the WHO change categorising system for grading the motility of sperm on 2010? Describe the new system.
Distinguishing between rapidly progressive motility and less rapidly progressive motility is technically quite difficult. A simple system for grading motility is recommended, which distinguishes progressive, non-progressive and immobile sperm.
PR (progressive) - sperm moving either linearly or in a large circle, regardless of speed.
NP (non-progressive) - swimming in small circles, flagellar force hardly displacing the head, or only a flagellar beat can be observed.
IM (immotile) - no movement.
The result of the 2010 motility grades relates poorly to the clinical picture. Fast and medium (a and b on previous WHO scale) give a better clinical picture. Velocity matters with regards to ability to conceive.
Describe how automation can aid the analysis of sperm concentration and motility.
These are essentially what we call CASA (Computer Assisted Semen Analysis) instruments.
Involves digital recognition of sperm from a video. A fixed depth slide is used with a fixed area/volume. This provides an answer in millions per ml.
Sperm swimming speed is assessed from a 1 second video using D/T=S.
These systems have been around for 20+ years but they used to have problems differentiating spermatozoa from other non-motile cells. They need to eliminate leukocytes, germinal cells, cell debris and epithelial cells, otherwise the system will underestimate the motile sperm percentage. For the system to be accurate it needs to be able to represent a portion of sperm correctly within a known volume.
Early systems such as HTM, Hobson Tracker proved unreliable. SQA and Nottingham sperminator are looking more reliable.
Describe how the Nottimham Sperminator automated analysis system works.
Sperminator uses a 25um scale that allows us to verify how far sperm have travelled on 1 second (more than 25um = grade A).
The system is very quick to analyse sperm (30 seconds for 200-400 sperm). The error rate is less than 10%.
Now moved on with automated system to try and validate results on clinic. As concentration of rapidly moving sperm in inseminate increases so does pregnancy. May be used to create thresholds regarding whether a particular sperm sample is motile enough for a particular procedure or would be better suited to another procedure.
Describe agglutination and aggregation with regards to sperm.
Agglutination is when motile sperm stick together by head to head or head to tail interaction in a mixed way. Agglutination tends to be due to the formation of anti sperm antibodies (5% patients). Agglutination can have a marked effect on motility grades and the sperm counts. We therefore need to assess each motility slide and estimate the proportion of agglutinated sperm. We then go ahead and perform a motility assessment on the free swimming portion of the sample.
Aggregation is the adherence of immotile sperm to each other or of motile/immotile sperm to mucous, debris or non sperm cells.
Describe vitality testing. When should it be performed? How is it performed?
The WHO manual recommends that a vitality test should be performed if less than 40% of sperm in the sample are motile (most labs only do it if only 1-2% are motile).
We tend to use eosin/nigrosin staining for vitality testing. If the cells exclude the dye it means they are alive, of they Stan red then they are dead. We can also use the Hypo-osmotic swelling (HOS) test and live cells will become swelled with coiled tails.
The eosin nigrosin test is rapid and unequivocal. However, once sperm have been selected as alive they cannot then be used therapeutically.
HOS is used for ICSI and enables live sperm selection. However, it can be subjective.
Why do we need to analyse sperm motility?
We need to provide an accurate measure of sperm motility because the concentration/number of progressively motile sperm is the most significant predictor of fertilisation and pregnancy.
Motility is simply about the swimming characteristics of the sperm.