What type of microscope is required to evaluate sperm motility?

Sperm motility refers to how well sperm can move – a critical factor in any livestock breeding program. Sperm that do not ‘swim’ properly will not reach the egg to fertilise it – a serious problem for breeders.

However, you can’t evaluate sperm motility properly with any old microscope.

For a proper assessment, you need to be able to clearly see your specimens while they’re still alive and healthy, which is difficult to achieve with a standard microscope.

Ideally, you’ll want to have a microscope with the following 5 features.

  1. Heated stage

Sperm samples need to be warm to be kept alive during your assessment.

Without sufficient warmth, the samples would quickly perish, making any motility evaluation futile. So, a microscope with a heated stage, either integrated or added, is essential.

Microscope Temperature Control Stage

If you’re working with samples from numerous species, you’ll need to ensure the stage temperature is adjustable. Different species require different temperatures.

  1. Phase contrast

Sperm samples are transparent and can be difficult to see with a standard microscope.

Normally, transparent samples are stained to make them easier to see but the process can damage or kill living organisms or cells. As motility inspection requires a healthy sample, many professionals use phase contrast microscopes instead of staining.

Phase contrast microscopy is a technique that turns the tiny phase shifts in light passing through a transparent sample into visible brightness variations in the image you see.


BM2000-PH Phase Contrast Microscope

Essentially, the image contrast will be much greater, and you’ll be able to see the sperm sample more easily and in more detail.

Essentially, the image contrast will be much greater, and you’ll be able to see the sperm sample more easily and in more detail.

Phase contrast also has no effect on specimens, so it can be safely used to view healthy samples in their natural state with no ill-effects.

  1. Magnification

You need a reasonable level of magnification for sperm evaluation – generally 400x magnification. This is usually achieved by having a 40x objective lens and a 10x eyepiece lens.

  1. Digital cameras and camera mounts

It’s an excellent idea to have a microscope with an integrated camera, dedicated camera mount or (at the very least) a digital microscope camera that can be attached to an eyepiece.

It’s good practice to record and document your work as you go, and it’s very easy to capture, save and monitor the movement of your specimens using a digital camera. It’s also convenient if you wish to send images or footage from the field to colleagues or specialists for consultations.

More importantly, a common method of motility estimation involves using long exposure photographs. You can assess the health of the sperm by inspecting the trails left behind by the long exposure time. It’s an easily measured, objective and repeatable approach.

Human Sperm under a Phase Contrast Microscope

Digital cameras have another advantage in that they can be used to transmit the live image to a nearby screen or monitor. If you prefer looking at a screen instead of looking down an eyepiece, this might be worth looking into. The ability to transfer images to big screens or smartboards can also be an excellent tool for teaching or training purposes.

  1. LED lighting

Heat from some forms of lighting (for example, halogen bulbs) can kill living samples but this is becoming less of a problem with the prevalence of LED lighting.

Most microscopes use LEDs – they’re long lasting, produce even light and generate very little heat. If possible, go with LED illumination.

Conclusion

Introducing a quality microscope to your farm, vet practice or fertility clinic will really improve the quality and accuracy of your results.

While you can make do with lesser microscopes, the features mentioned above will have a big impact on your results and the quality of your work life.

 

 

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