In vivo preservation of tissues may exist as a problem in experimental and clinical research. Adipose tissue, nerves, and vessels are the tissues that are usually preserved in vivo for future use or for the evaluation of results in experimental research. Limited Volume and difficult conditions in such areas in animal models usually create disappointing results, because of the difficulty in distinguishing the experimental from the surrounding tissues; the insufficiency of the volume of space; and the lack of compliance in animals. A new rat model for in vivo preservation studies is described. A muscular pocket designed between the external and internal oblique muscles is a good choice as an animal model for tissue preservation in plastic surgery research.