I am trying to decide whether I should source new glass slide covers for my haemocytometer or find appropriately sized coverslips. The coverslips are cheap but get broken regularly. The proper lids are relatively expensive but seem thicker and less likely to break.
Should I get both and only let the project students use the coverslips?
Right Leoploldo! You cannot use ordinary coverslips with a haemocytometer as they will distort due to the capillary force of the liquid under the coverslip unless it is measured to the precise amount to fill the space under the coverslip. Usually you allow the space to be filled by capillarity in which case there is always a slight (and variable) downward pull on the coverslip. It is also much more difficult to get a normal coverslip to attache tightly (so that you can see Newton's rings) without risking breaking the coverslip. Use the proper coverslip otherwise you are not showing the students the correct procedure.
I have found the appropriate slips to work best as they are more robust and don't bend with surface tension. This can reduce the volume of the chamber and lead to overestimation of the counting.
I agree - you should use the haemocytometer cover slips to ensure you're counting the correct volume.
If you want an accurate count of the cells you should use the cover slips designed for the haemocytometer, the cover slips for slides are not consistent and tend to bend ever so slightly with surface tension. If you are counting cells use the right coverslip, if you are just looking at cells it may not matter.
It might be fun to compare counts using the heamocytometer cover slip versus a regular #1.5 coverslip, but to be accurate you have to use the heavier heamocytometer cover slip.
Heamocytometer cover is much more durable that coverslip, n convenient too
Hemocytometer cover should always be used while counting with a hemocytometer, in my opinion. While counting, the microscope objective generally touches the cover slips and sometimes for fine focussing puts pressure on the cover slips. Normal cover slips cannot withstand the pressure and breaks, which can damage the objective and as well as spoil your sample and effort. So, special hemocytometer coverslips have that durability to bear the objective pressure and keep the sample intact and clean for counting.
Hope this explanation helps...!!!
Buy the proper ones they as others have said are much tougher, should very virtually never break, if treated well and if they do it is easy to clear up unlike the thin tiny shards of a cover slips.
As long as your coverslip either the specific one or the thinner one is firmly attached on the hemocytometer the volume aquired for the counting should be the same. To do this you make sure that both coverslip and the hemocytometer are clean and dry. Then blow a moist breath (like you did on the window as a child to draw smiley faces) and then gently press the coverslip on the hemocytometer. This should be sufficient to secure the coverslip on the hemocytometer. You should be able to see a rainbow effect if you tilt it a bit on the light. Now you are ready to add your cells.
However,I do agree with everyone that the proper slide is better and durable although like with every thin glass item we should be extra careful.
Good luck with your decision!
If the haemocytometer going to be used by students, I recommend you employ the specific covers, not only for accuracy, but also and mainly for biosafety reasons. You will avoid many accidents by breaking the coverslip.
Hi Triona
In fact, whether you are going to use a glass cover slip or haemocytometer specific cover, i think both are expected to be broken with more usage. So, compare between the count given by using both cover slips and any avialable cell counter. If there is no big difference why you should not use the economical one with some care. Also, i agree with everyone that the proper slide is better and durable but both coverslips are raised on one depth which is 0.1 mm when firmly attached to the chamber bridgs.
Good luck
With specific cover you can apply the appropriate pressure without breaking it, so the volume you read is more accurate
Right Leoploldo! You cannot use ordinary coverslips with a haemocytometer as they will distort due to the capillary force of the liquid under the coverslip unless it is measured to the precise amount to fill the space under the coverslip. Usually you allow the space to be filled by capillarity in which case there is always a slight (and variable) downward pull on the coverslip. It is also much more difficult to get a normal coverslip to attache tightly (so that you can see Newton's rings) without risking breaking the coverslip. Use the proper coverslip otherwise you are not showing the students the correct procedure.
I have used both and have not found any issues with using the cheaper brands. I agree with some of the others here that a comparison could be useful if you really want to convince yourself that there is no difference. Having said that I belief that error due to the method itself probably far outweighs any differences due to generic cover slips.
I agree with those above who state that the special coverslips should be used. They are thicker for a reason. The stiffer glass allows the geometry, and therefore the included volume, of the counting "chamber" formed by the coverslip to be more accurate. I seem to remember that the issue was possible floating rather than warping, but I can't swear to it. The thicker slips are more expensive, and kids will still break them, but accuracy requires that they be used. Then again, Florian also has a point. Using these darned things is so tedious that I suspect few people are able to strictly adhere to the exact procedure in regard to which lines your cells are touching vs which should and shouldn't be counted and so on. So the slight volume variation you supposedly get with ordinary cover slips might not make much actual difference in your results.
The specific haemocytometer coverslip is required for accurate cell counts. It is designed so that the space between the coverslip is known, therefore ensuring that the volume of sample introduced into the chamber is known. Using any other coverslip will render counts inaccurate, as the volume will not be fixed.
My understanding is that regular coverslips will not actually give you the same volume because they are too light. If this is just a teaching lab, then the difference won't matter. If you need accurate cell counts, you should use the proper one. If you compare them side by side, you will see the differences. You could also try them side by side to see if you get the same counts.
(I hit Add to soon) That is, you could make it a really good exercise for the students to do the side by side comparisons, find the answer, and determine the uncertainties. I think it would be a great lab!
Most of the error in counting is due to floating of the regular coverslip when more sample is injected into the chamber (forceful rather than capillary action).
If you decide to use regular coverslips, then do ensure that the coverslip is secured to the haemocytometer by applying water droplets on the bridges and slightly pressing the coverslip against the haemocytometer.
This will ensure that the sample enters the chamber due to capillary action only!
If trained properly the normal thick coverslips should last for years. The knack of getting "Newton's Rings" (as mentioned by Ian Freshney) again is easy. Mostly people have problems getting the rings because the Haemocytometer is not clean and is smeared by grease from grubby fingers. Again I agree with everyone that suggests that the thinner coverslips (used by people doing immunohistochemistry) will not produce the required volume and give accurate counts.
Using a haemocytometer is easy and has been the most common way of counting cells for the past 36 years that I have been counting cells......you just need a gentle touch!!!!!
What do you all think about disposable coverslips? - If it is just to show how counting works it could be cheaper to use these with students. Depending how often something breaks and how many counts the students should do... sure you want to show the good old haemocytometer as well.
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