Electronic determination of size and number in isolated unfixed adipocyte populations.

Adipose tissue cellularity and metabolism are traditionally expressed in terms of mean cell size and number. The need for a simple method allowing rapid determination of cell size and number of freshly isolated, unfixed adipocyte preparations led us to compare estimates of cell size determined by the established method of optical sizing to a proposed method of electronic cell sizing and counting. In collagenase-isolated, unfixed adipocytes whose mean diameters ranged from approximately 40 to 65 microns (obtained from healthy rats weighing 100-360 g) the electronic method provided estimates of the mean cell diameter and size distribution that did not differ from the optical sizing technique. Estimates of mean cell diameter and cell number by the electronic method were rapid and reproducible (coefficients of variation 0.5 and 3.8%, respectively) and a less than 20 sec delay until sample analysis, after mixing of the adipocyte suspension, did not alter these estimates. Electronic determination of cell size and number, using freshly isolated, unfixed rat adipocyte populations (mean cell diameter less than or equal to 60 microns), is rapid and reliable. It will be particularly useful for studies of hormone binding and transport processes where it may be necessary to tightly control cell density.