Piwil1-EGFP-iCre mice are generated via genome editing by replacing the TAA stop codon of the mouse Piwil1 gene with an HA tag-3xEAAAK-EGFP-IRES-iCre cassette, enabling expression of iCre recombinase (codon-optimized Cre) and EGFP under the control of endogenous Piwil1 regulatory elements. The expression patterns of iCre recombinase mirror that of the endogenous Piwil1 gene. When crossed with mice containing loxP sites, Cre-mediated recombination between loxP sites is expected to occur in Piwil1-positive cells of the offspring. Beyond Cre-loxP gene recombination, this model allows EGFP-based fluorescent tracing.