The goal of the research is to obtain MR images in evolving physiological states, using the properties of hyperpolarized 129Xe in (a) cell and tissue compartmentalization, (b) dramatically time-dependent distribution, and (c) response of NMR chemical shift, T1, and T2 to environment, O2, and exchange kinetics, to obtain detailed anatomical images mapped with functional information. %%% Magnetic resonance imaging is important to basic as well as applied research in the biological sciences. Current imaging methods depend on subtle differences in the magnetic properties of water molecules in biological materials. The available contrast is quite low and the ubiquitous presence of water prohibits its use, except in some flowing systems, to measure diffusion and compartmentalization. The proposed research makes use of the extreme ease of magnetic resonance detection of hyperpolarized Xe atoms and the fact that Xe distributes rapidly in biological systems and similarly washes out rapidly. If successful, these studies could lead to substantial changes in how magnetic resonance imaging experiments are organized and add considerably to the method's informational content.