This research is the third major effort in a collaborative research program on the anatomy of ray-finned fishes (actinopterygians), a group containing about half of living vertebrates. This project concerns detailed comparative descriptions of the early embryology of a cluster of four organ systems that develop at the rostral tip of the head including the hypophysis (pituitary), nose, adhesive and hatching glands. The adenohypophysis has been stressed because it is both central to interpreting the development and history of the vertebrate head and unites studies of comparative anatomy, embryology, and endocrinology. %%% For approximately 50 years comparative embryology of ray-finned fishes have been neglected. The use of scanning electron microscopy and modern histology to study comprehensive series of embryos of several primitive ray-finned fish will help to resolve many century-old controversies. In addition, fishes are better suited for detailed embryological and developmental studies of organ systems, and the data produced from these comparative data will provide valuable information that will allow one to interpret patterns of development of the vertebrate head and its many organ systems.
