Immunocytological evidence for oxytocin neurons in the human fetal hypothalamus

The use of antibodies against oxytocin or neurophysin enabled the detection by immunocytochemistry of oxytocin-neurophysin neurons in the hypothalamus in the human fetus. The perikarya of these neurons are located in the paraventricular and supraoptic nuclei. Immunoreactive neurons occure in the median eminence. The neurophysin immunoreactive neurons were more numerous than the oxytocin immunoreactive neurons. The specificity of the immunocytological reaction was controlled. The first oxytocin-neurophysin neurons are seen as early as the 14th week of gestation.