Direct determination of the growth rate of Drosophila imaginal discs

A simple technique is described which allows the number of cells in the imaginal discs of Drosophila melanogaster to be determined directly, by dissociation of the tissue into single cells. This technique was used to determine the growth rates for the eye‐antenna, wing, leg, and haltere discs during the second and third larval instars. The results obtained for the number of cells present at particular stages and for the growth rates during this period are similar to those determined previously using either indirect or more tedious procedures.