The Stra8 gene encodes a meiosis-inducing factor required for the transition of male and female germ cells into meiosis. It is involved in several processes, including the activation of meiosis, cellular responses to retinoic acid, and the development of germ cells. Stra8 expression is limited to germ cells before meiosis in both sexes. In this model, the ‘P2A-ZsGreen1-T2A-Cre’ cassette is inserted before the stop codon of the Stra8 gene. This insertion mimics the endogenous gene expression pattern without disrupting the function of the Stra8 gene. When crossed with mice containing loxP sites, the offspring can undergo Cre recombinase-mediated sequence recombination between the loxP sites in spermatogonial cells. Cre enzyme induces recombination starting from A1-type spermatogonial cells (pre-meiosis). The heterozygotes are viable and fertile.