Abstract
This chapter describes two preparations developed in the laboratories that in large part replicate the complexity of the embryonic milieu and the numerous factors that affect cell interactions and guidance, and that nonetheless offer the pliability and visibility of tissue culture. These preparations use the avian embryo that is particularly valuable in elucidating elements of motoneuron and neural crest cell guidance. While slice preparations are used in chick for other purposes, the preparations described are particularly useful for dissecting guidance interactions by visualizing movements and interactions of cells and growth cones either in situ or seeded onto complex embryonic environments. These slices, like the better studied slices of the central nervous system used for neurophysiological studies, maintain many characteristics of the intact embryo and allow developmental and physiological events to be directly observed and manipulated in a more normal environment. Somite strips are a hybrid in vivo–in vitro assay that exposes anterior and posterior sclerotomes to view and yet retains in culture both the segmental architecture and the typical molecular characteristics, such as differential binding to peanut agglutinin lectin. Labeled neurons or cells sprinkled directly on the strip are visible and have direct access to guidance cues.
