What is the primary function of a hemocytometer in lab practice?

What is the primary function of a hemocytometer in lab practice?

• A. Counting chambers used to protect the number of cells per microliter
• B. A device for measuring hematocrit levels
• C. A device used to inoculate bacterial plates
• D. A device for scoring blood smear morphology

Answer: (A)

The main idea is that a hemocytometer provides a precisely defined counting chamber so you can convert how many cells you see under the cover slip into a concentration per unit volume. Its grid and fixed depth create a known volume, so after diluting the sample and counting cells in the designated squares, you multiply by the dilution factor and by the reciprocal of that known volume to get cells per microliter. This standardization makes it a reliable way to estimate cell density in suspensions such as blood cells, cultured cells, or yeast. It’s not used for measuring hematocrit (that’s done by spinning a capillary tube to separate cells and plasma), nor for inoculating bacterial plates, nor for assessing blood smear morphology.

The main idea is that a hemocytometer provides a precisely defined counting chamber so you can convert how many cells you see under the cover slip into a concentration per unit volume. Its grid and fixed depth create a known volume, so after diluting the sample and counting cells in the designated squares, you multiply by the dilution factor and by the reciprocal of that known volume to get cells per microliter. This standardization makes it a reliable way to estimate cell density in suspensions such as blood cells, cultured cells, or yeast. It’s not used for measuring hematocrit (that’s done by spinning a capillary tube to separate cells and plasma), nor for inoculating bacterial plates, nor for assessing blood smear morphology.