Drosophila embryo collection.

INTRODUCTIONA number of factors make the early Drosophila embryo particularly amenable to cellular analysis. First, large numbers of specifically staged embryos are easily collected from normal and mutant stocks. Also, the morphological and cellular events of embryogenesis have been characterized extensively. For example, directly after fertilization, the embryo proceeds through a series of rapid nuclear divisions that rely on the highly coordinated dynamics of the microtubules, microfilaments, and other cytoskeletal components. During this time, critical events that establish the axis and patterning in the embryo occur. These events have been thoroughly described and provide an excellent resource in which to analyze the primary cellular defect in newly isolated mutations. Analysis of fixed samples allows many more embryos to be examined in a single session on the microscope, and the fixed preparations are stable for long periods. If fluorescent probes are used, anti-quenching reagents in the mounting media allow extensive documentation of the samples without signal deterioration. Double- and triple-labeling for colocalization studies are easily performed. Finally, images can be recorded from fixed samples over multiple planes for three-dimensional reconstructions. This protocol describes the most common and generally applicable procedure for collecting Drosophila embryos for fixed cellular analysis.