The disposable Countess Cell Counting Chamber Slides offer convenience in automated cell counting for processing multiple cell samples, busy cell culture facilities, and easy disposal of contaminated or hazardous samples. They also eliminate the risk of contamination from residual samples. After use, Countess slides can be disposed of as standard biohazard waste. Unlike a hemocytometer, there is no need to clean Countess slides before or after use.

Each Countess Cell Counting Chamber Slide has two separate, enclosed chambers for counting one sample in duplicate or two different samples. Cell counting occurs in a central location of the counting chamber. The volume counted is 0.4 μL, the same as counting four 1-mm2 squares in a standard hemocytometer.

The Countess Automated Cell Counter works in three simple steps:

• Mix 10 μL of sample with 10 μL of trypan blue stain or other desired reagent, including ReadyCount™ stains, and pipet into a disposable Countess chamber slide
• Insert the slide into the instrument
• Press 'Count'

That's it—get the total cell count, percent viable cells, and average cell size in as little as 30 seconds.

The Countess Cell Counting Chamber Slides include two vials of trypan blue for brightfield automated cell counting and viability analysis (Cat. Nos. C10228, C10312, C10314, C10313, and C10315). The slides can also be purchased as 1 box of 50 slides without trypan blue (Cat. No. C10283) for use with other stains such as the ReadyCount fluorescent stains. The trypan blue vials are also available for purchase without slides (Cat. No. T10282).

Trypan blue staining is a long-standing and widely used method to measure cellular viability by identifying dead cells. Live cells with intact membranes exclude the dye, while dead cells with compromised membranes become stained, allowing for the differentiation and counting of live and dead cells to assess cellular viability. Trypan blue staining is the method employed by the Countess family of automated cell counters for cell counting, and this 0.4% trypan blue solution is the correct concentration for use on these instruments.

Note: Precipitates are quite common in trypan blue, and typically increase with storage time and freezing. The three approaches below may help minimize trypan blue precipitate in your cell counting samples:

• Sterile filtration of trypan blue using 0.3-micron filter
• Centrifugation or passive settling (avoid mixing or vortexing trypan stock solutions)
• Gentle warming of the 1-mL trypan solution to 37°C for 10 minutes

The Countess Disposable Slide Holder is used to hold the Countess disposable slides. It is designed for use with Countess II FL, Countess 3, and Countess 3 FL automated cell counters and is included with these cell counters. A replacement Countess Disposable Slide Holder (Cat. No. AMEP4745 ) is available for separate purchase. This Countess Disposable Slide Holder is not compatible with the Countess Reusable Slide (Cat. No. A25750).