Mouse Monoclonal. Ready-to-use. Intended for in vitro diagnostic (IVD) use. OCT 3/4 is a transcription factor that has been recognized as fundamental in the maintenance of pluripotency in embryonic stem cells and primordial germ cells. It has been proposed as a useful marker for germ cell tumors (GCT) that exhibit features of pluripotentiality (seminoma/dysgerminoma, germinoma and embryonal carcinoma. OCT 3/4 immunostaining has been shown to be sensitive and specific for GCT, whether in primary gonadal or extragonadal sites or in metastatic lesions.