Developmental expression of oxytocin receptors in the neonatal medulla oblongata and pons

► The distribution of oxytocin receptors (OTRs) in the postnatal brain stem of rats was examined by immunohistochemistry. ► OTR-immunoreactive structures were distributed densely in the sensory nuclei and others except motor nuclei by postnatal day 10. ► OTR-immunoreactive structures were observed in the neuronal Golgi apparatus by using electron microscopy. ► The present study suggests that transient type of OTR may function for neuronal development in the neonatal period.