Oct-4 is a transcription factor that plays a role in controlling and preserving pluripotency in embryonic stem cells and primordial germ cells. Oct-4 immunoreactivity has been observed in gonadal and non-gonadal seminomas, dysgerminomas, and embryonal carcinomas. Furthermore, the immunohistochemical identification of Oct-4 helps in assessing intratubular germ cell neoplasia (IGCN).