Royal Victoria Hospital 1 article published in JoVE Biology High Resolution Whole Mount In Situ Hybridization within Zebrafish Embryos to Study Gene Expression and Function Babykumari P. Chitramuthu1,2, Hugh P. J. Bennett1,2 1Endocrine Research Laboratory and Department of Medicine, Royal Victoria Hospital, 2McGill University Health Centre Research Institute The zebrafish, a small tropical fish, has become a popular model for studying gene function during vertebrate development and disease. The temporal and spatial expression of target genes can be determined by in situ hybridization. Our improved protocol allows for the detection of low abundant transcripts with low non-specific background signal.