MUHWA Cell Counting Chamber Slides — 2-Chamber, 50/Pack, Countess Compatible
If you count cells with a Countess — or an EVE, LUNA, or any counter that takes the standard disposable slide format — these are the slides you load. Each slide has two independent counting chambers. Pipette 10uL of your trypan blue-stained suspension into the loading port on either chamber. The sample flows by capillary action across a fixed-depth counting area. Insert into the instrument, focus, count. Two chambers per slide — count both and average for your reported value. Fifty slides per pack, 100 counts total.
The chamber depth is fixed at 100um, same as the OEM slides. The counting grid dimensions match the instrument's calibration. If you've been using the manufacturer's slides and switch to these, your counts should be consistent — same volume, same depth, same grid area.
Counting Protocol (Trypan Blue Exclusion)
1. Prepare your cell suspension. Harvest, wash, and resuspend your cells in an appropriate volume. For adherent cells, trypsinize and quench with complete medium. For suspension cultures, take an aliquot directly. Aim for a concentration between 1x10^5 and 1x10^7 cells/mL — above this, dilute before counting. Below this, you'll count too few cells for statistical reliability.
2. Mix with trypan blue. Take 10uL of cell suspension, add 10uL of 0.4 percent trypan blue (1:1 dilution). Mix gently by pipetting up and down 2-3 times. Don't vortex — it lyses fragile cells. Let it sit for 1-2 minutes at room temp. Longer than 5 minutes and trypan blue starts to become toxic — dead cell count will creep up.
3. Load the slide. Pipette 10uL of the stained mixture into the loading port on chamber A. Capillary action draws it in — you'll see the chamber fill. If it doesn't fill completely, try angling the pipette tip slightly against the port edge. Load chamber B with another 10uL from the same tube. Don't overfill — excess will spill into the other chamber or out the vent port.
4. Insert and count. Place the slide in the Countess (or EVE/LUNA) with chamber A in the light path. Focus on the counting grid. The instrument automatically discriminates live (round, bright center, exclude trypan blue) from dead (blue, irregular, take up dye) cells. Record the live count, dead count, and viability percentage for chamber A. Repeat for chamber B. Average the two live counts for your final number. If chamber A and B differ by more than 20 percent, re-mix your sample and count again — uneven mixing is the usual cause.
What Fits
| |
|---|
| Chambers per slide | 2 |
| Sample volume per chamber | 10uL of stained suspension |
| Chamber depth | 100um (fixed) |
| Slides per pack | 50 (100 counts total) |
| Compatible instruments | Countess I, II, II FL, 3, 3 FL. Also EVE, LUNA, and other counters using standard disposable slide format |
| Staining method | Trypan blue exclusion (0.4 percent w/v, 1:1 dilution with sample) |
| Disposal | Single-use. Discard as biohazard waste after counting |
What to Watch For
Bubbles in the chamber. If you see a bubble trapped in the counting area, you'll get a low count because the bubble displaces sample from the grid. Reload that chamber. Bubbles happen more often with cold samples or if you pipette too fast. Let the cell-trypan mixture warm to room temp before loading.
Uneven cell distribution. If chamber A gives 5x10^5 and chamber B gives 8x10^5, your sample wasn't mixed. Re-pipette the original tube to resuspend settled cells, take a fresh aliquot, stain, and recount. Cells settle in the tube within 30-60 seconds — mix immediately before each aliquot.
Trypan blue precipitate. Old trypan blue develops crystalline precipitate. Filter it (0.2um syringe filter) or replace the bottle. Particulate in your counting chamber looks like dead cells to the instrument.
Viability drift over time. If you count the same stained sample at 2 min vs 10 min, the viability will be lower at 10 min — trypan blue is cytotoxic on extended exposure. Count within 1-5 minutes of staining for accurate viability.
FAQ
Do I need to calibrate my Countess for these slides?
No. The chamber depth and grid dimensions match the OEM slides. If your instrument is calibrated for the standard disposable slide format, these read identically. If you're switching from reusable hemocytometers, you will need to run a few side-by-side comparisons initially to confirm your dilution factors transfer correctly.
Can I reuse these slides?
No. They're single-use. The chamber is a closed capillary system — once loaded, you can't effectively clean and dry the internal surfaces without damaging the optical quality of the counting area. The cost per count is low enough that cleaning isn't worth the time or the cross-contamination risk.
What if my cell concentration is too high or too low?
The instrument works best between 1x10^5 and 1x10^7 cells/mL (before trypan blue dilution). Below 1x10^5, you're counting fewer than ~10 cells per grid square and the statistical noise is high — pellet and resuspend in less volume. Above 1x10^7, cells overlap on the grid and the instrument can't discriminate individual cells — dilute with PBS or medium and recount. If the instrument gives a "too few cells" or "too many cells" error, adjust your dilution accordingly.
Can I use fluorescent stains (AO/PI, DAPI) with these slides?
These slides are designed for brightfield counting with trypan blue. If your counter has fluorescence capability (Countess II FL, 3 FL), check whether the slide plastic autofluoresces at your excitation wavelength. For AO/PI viability counting with the FL models, test one slide first with your stain and excitation settings. Most users find these work, but the autofluorescence background may be slightly different from the OEM slides.
