Proper handling and fixation of gastrointestinal tissues of birds

Much attention is directed to the development and adaptation of the avian g astrointestinal system in order to evaluate feed additives and product cand idates. Specific parameters going beyond cell population and morphology are repeatedly used for evaluation purposes. Measurements of the potential abs orptive qualities of the intestine are compared, and good quality cross-sec tions of each specimen are critical. Good cross-sections with distinct and complete villi are dependent on fixation. Fixation variables include time, temperature, size of specimen, density of specimen, selected fixative, pene tration, total volume of fixative, agitation of fixative and tissue, and th e condition of the specimen when placed into fixative.