pdf-1 was expressed in both sexes in the head interneurons SAAV, SAAD, SIAV, AVB, AIM, RMG and two other unidentified ciliated neurons (possibly ASK and AFD). In the tail,
pdf-1 was consistently expressed in interneurons PVN, LUA, PVT, and the pair PVS and PVU (referred to as PVP left and right in the hermaphrodite). Expression was also observed in male-specific neurons (ventral cord neurons CP7 and CP8, and PDC) and in one unidentified interneuron, possibly PVX, in the pre-anal ganglion.