Two methods that permit scientists to examine critical stages in early embryogenesis are featured in this month's release of Cold Spring Harbor Protocols.
The methods, which are freely accessible online (www.cshprotocols.org), describe how to fluorescently tag cells in very young embryos. These cell-tagging techniques, combined with sophisticated imaging methods, permit scientists to visualize even subtle movements of individual cells in the embryos, as they morph, divide, and migrate.
The first protocol, available at www.cshprotocols.org/cgi/content/full/2007/24/pdb.prot4915, describes a step-by-step approach to label specific cells of live mouse embryos using fluorescent dyes called carbocyanine dyes. Carbocyanine dyes are ideal for this purpose because they can be used on living embryos. After labeling, the embryos are imaged to reveal the precisely coordinated patterns of cell movements as the embryo develops.
The protocol was contributed by Dr. Patrick Tam's group from the University of Sydney, Australia (www.medfac.usyd.edu.au/people/academics/profiles/ppltam.php). His lab uses these techniques to investigate the timing and patterning of cell movements during gastrulation, which is a critical stage in early embryonic development. Also, by performing this procedure in embryos that are both normal and genetically mutated, they can better understand the functions of specific genes involved in gastrulation.