Birds

Abstract

For practical and historical reasons the study of bird development is almost synonomous with the study of the development of the chick. The practice of rearing and keeping chickens is probably as old as society itself. By the time of Pliny (23 – 79 A.D.) several methods of incubating eggs appear to have been well established, and on the scientific side, the early history of embryology is very largely bound up with the study of chick development (Fabricius 16th C; Harvey 17th C; Wolff 18th C). This intense interest in chick development extends of course to modern times, where the experimental analysis of organogenesis, especially limb development, owes much to work on this animal. Despite this wealth of information however, the usefulness of the chick as class material for large groups is rather limited. At an elementary level it is probably best suited for demonstrating the main features of the early development of vertebrate structure. In this chapter we have concentrated mainly on this aspect and give accounts of methods for examining and culturing the early chick blastoderm. Some attention is also paid to the embryonic membranes and in this connection the procedure for chorio-allantoic grafting is described. Before describing this practical work in detail, a few general points need to be made.