Counting cells in sectioned material: a suite of techniques, tools, and tips.

This unit presents protocols to obtain accurate estimates of cell density and cell number in sectioned material by using a light microscope. The "optical disector" or "3-D counting method" is described, followed by Abercrombie's less commonly used two-section comparison (TSC) method. These basic protocols are accompanied by four support protocols: one for celloidin embedding, which renders superb morphology, one for point counting, which is important for volume measurements and is almost always used in conjunction with the disector or 3-D counting, one for handling the potential problem of z-axis distortion and the consequences that this error can have on density estimates and sampling tactics when using the disector, and finally, one that provides a guide for calibrating and verifying estimates obtained by counting methods.