The invention provides methods of introducing heterologous cells into
fish. After introduction cells remain viable, and in some instances
proliferate, for sufficient time to conduct a variety of analyses on the
heterologous cells or the fish or both. Such methods are useful for
screening potential drugs for toxicity toward introduced cells or for
capacity to stimulate differentiation and/or proliferation of introduced
cells. Such methods are also useful for diagnosing the presence of small
quantities of cancerous cells or pathogens in patient tissue samples.
Such methods are also useful for culturing cells for subsequent use in
cell or tissue engineering.