The small intestinal epithelium is continuously replaced by a new cell from the crypts, which makes this organ the fastest regenerative organ in a body. Fast-cycling intestinal stem cells (ISCs) marked with leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5) are located at the bottom of the crypts and proliferate once every day to provide new cells. Despite the continuous renewal and turnover of the small intestinal epithelium, the intestinal crypt maintains a ‘soccer ball-like’, alternating pattern of stem and Paneth cells at the base of the crypt. To study the robustness of the alternating pattern, we used intravital two-photon microscopy in mice with fluorescently-labeled Lgr5+ ISCs and precisely perturbed the mosaic pattern with femtosecond laser ablation. The work presented in this dissertation provides a new type of behavior of Lgr5+ ISCs in addition to the proliferation and self-renewal, which is critical to maintain integrity of small intestinal epithelium in homeostasis.