The purpose of this program announcement (PA) is to encourage the submission of applications for research to enhance animal stem cells as model biological systems. Innovative approaches to isolate, characterize and identify totipotent and multipotent stem cells from nonhuman biomedical researchanimal models, as well as to generate reagents and techniques to characterize and separate those stem cells from other cell types is encouraged. Studies involving human subjects are not allowed under this PA. This PA supersedes PA-02-147 issued earlier by the NCRR.