COMPUTER MORPHING OF SCANNING ELECTRON-MICROGRAPHS - AN ADJUNCT TO EMBRYOLOGY TEACHING

Traditional embryology courses demand considerable expenditure of time and effort from students to master the spatial awareness skills neces sary to create three-dimensional mental images from two-dimensional se rial sections. Then students must imagine a movie sequence of the chan ges which take place during normal development. Further steps are requ ired to relate this information to the clinical situation. As more med ical and dental schools move towards problem-based curricula, more eff icient methods of improving understanding of embryology are needed. Th e development of many organs can be studied using scanning electron mi crographs of embryos at different ages. These high quality images are more easily interpreted by our students than histological sections and the understanding achieved more readily applied to clinical problems. Still more beneficial would be the provision of moving images showing the actual changes happening. We decided to use computer morphing tec hniques to prepare movie sequences showing development of the face and palate. For each, four scanning electron micrographs of appropriately -sized sheep embryo heads were taken at the same magnification and ori entation to use as start and end points of morphing sequences. After u sing retouching techniques to colour the separate processes, further s equences were prepared. The discipline of maintaining the same magnifi cation throughout and the possibility of directly observing changes be tween stages revealed same surprising growth patterns. This technique is adaptable to any area of biological development where pre- and post -illustrations are available. Animations can be presented on computer or on video and incorporated into programs. Student feedback has been very favourable.