The Morphology/Physiology Core will serve all sections of the Program Project. The Core will provide morphologic, morphometric, immunochemical and functional evaluation of transgene expression patterns and muscle and innervation responses in transgenic animals. In addition, this Core will be responsible for ALV vector transfer into muscles of fetal, neonatal and adult ALV receptor mice. Viral stocks will be prepared in Dr. Hughes lab at NCI Frederick and sent, frozen, to Philadelphia for injection into animals. Evaluation of the structural and functional response to vector mediated gene transfer in receptor animals will also be performed in this core.