This report details the validation of a polyclonal rabbit anti-Jagged1 antibody for immunofluorescence applications in human liver, stomach, and rat spleen tissues. The report describes the immunofluorescence protocol used, including tissue processing, antigen retrieval, blocking, primary and secondary antibody incubations, counterstaining, mounting, and visualization under a fluorescence microscope. Images show staining of Jagged1 protein in red with DAPI nuclear counterstain in blue.