Which instrument is a counting chamber used to estimate cell concentration per microliter?

• A. Hemocytometer
• B. Hematocrit tubes
• C. PCV card reader
• D. Standard WBC counting device

Answer: (A)

A counting chamber provides a precisely defined, small volume under a microscope, so counting cells in that known area lets you calculate how many cells are in one microliter of the original sample. The hemocytometer is the standard instrument for this purpose because it has the ruled grid and fixed depth that define a specific volume, enabling the calculation of cells per microliter after applying any needed dilution factors. This approach is essential for estimating cell concentration in clinical labs, whether for white or red blood cells. Other options aren’t counting chambers designed for direct concentration measurements: hematocrit tubes and related readers assess packed cell volume after centrifugation, not cell counts in a known microscopic volume, and a generic WBC counting device isn’t the instrument used for this purpose.