Harvard Stem Cell Institute 3 articles published in JoVE Developmental Biology Generation of Parabiotic Zebrafish Embryos by Surgical Fusion of Developing Blastulae Elliott J. Hagedorn1,2, Jennifer L. Cillis3, Caitlyn R. Curley3, Taylor C. Patch3, Brian Li1,2, Bradley W. Blaser1,2,7, Raquel Riquelme1,2, Leonard I. Zon1,2,4,5,6, Dhvanit I. Shah1,2,3,4,5 1Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, 4Harvard Stem Cell Institute, 5Broad Institute of Massachusetts Institute of Technology, 6Howard Hughes Medical Institute, 7Division of Hematologic Malignancies, Dana-Farber Cancer Institute This protocol provides step-by-step instruction on how to generate parabiotic zebrafish embryos of different genetic backgrounds. When combined with the unparalleled imaging capabilities of the zebrafish embryo, this method provides a uniquely powerful means to investigate cell-autonomous versus non-cell-autonomous functions for candidate genes of interest. Immunology and Infection Normal and Malignant Muscle Cell Transplantation into Immune Compromised Adult Zebrafish Inês M. Tenente*1,2,3, Qin Tang*1,2, John C. Moore1,2, David M. Langenau1,2 1Molecular Pathology, Cancer Center and Center for Regenerative Medicine, Massachusetts General Hospital, 2Harvard Stem Cell Institute, 3GABBA - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto Here, we present a protocol for cell transplantation of zebrafish skeletal muscle and embryonal rhabdomyosarcoma (ERMS) into adult immune compromised rag2E450fs homozygous mutant zebrafish. This protocol allows for the efficient analysis of regeneration and malignant transformation of muscle cells. Medicine Sequential In vivo Imaging of Osteogenic Stem/Progenitor Cells During Fracture Repair Dongsu Park1, Joel A. Spencer2, Charles P. Lin2, David T. Scadden1 1Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Stem Cell Institute, 2Wellman Center for Photomedicine and Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School Quantitative measurement of bone progenitor function in fracture healing requires high resolution serial imaging technology. Here, protocols are provided for using intravital microscopy and osteo-lineage tracking to sequentially image and quantify the migration, proliferation and differentiation of endogenous osteogenic stem/progenitor cells in the process of repairing bone fracture.