part of develops from secondary spermatogonium primary spermatocyte polar primary spermatocyte fly_anatomy.ontology Early primary spermatocyte with a spherical, asymmetrically placed nucleus and with mitochondria aggregated at the pole of the cell opposite the nucleus. The second nuclear membrane has started to form, the nucleolus is compact with few cavities and the centrioles are in the central region of the cell. polar spermatocyte FBbt:00057167 polar primary spermatocyte cyst