There is a way to count cells, measure their fluorescence, and even sort out specifically labelled sub-populations of cells?

Flow Cytometry passes individual cells inside a thin stream of liquid through a light cell that exposes the cells to different laser lines. Fluorescence, as well as light scattering can be detected.

Cell sorting uses a modified flow cytometer. The thin stream has a charge applied and if an individual cell in the stream of liquid meets specific criteria, as the charged stream passes from the light cell it goes through a pair of electrodes and a droplet from the stream (containing the cell of interest) is deflected so that the droplet goes into a collection tube.

Flow cytometry can be performed on blood, cells from culture, and digested tissue sections.

The UA Cancer Center and the RII Core Facilities jointly operate the only Cytometry core on campus. In addition to cytometry, there is a BSL2 cell sorter capable of sorting four separate sub-populations, as well as a new imaging cytometer. For more information see: https://cancercenter.arizona.edu/researchers/shared-resources/flow-cytom... (or on iLab at: https://ua.ilab.agilent.com/service_center/show_external/4407).

A short tutorial on how a flow cytometer works (Oregon State University)