Pituitary hormones are released in the blood stream in pulses. This pulsatility prevents both secretory machinery fatigue and target tissue desensitization, and reflects the intermittent electrical activity of hypothalamic neuroendocrine cells. It has proved difficult to decipher the mechanisms shaping the activity of neuroendocrine cells because they are often anatomically dispersed or integrated into complex networks. In terms of structure-function relationship, neuroendocrine cells are distributed along the third ventricle and can be viewed as secretomotor output units linked to their target organs via a neurovascular synapse. It is thought that their afferent command either partially or fully shape the pulsatile rhythm, and a hypothesis (Brain Res Rev 41:153) posits that a determinant set of periventricular nuclei harbour neuroendocrine central pattern generator (CPG) networks driving the neuroendocrine cells. Over the passed years (JNeurophy 76:2772, JN 18:6641, EJN 11:1960 and 17:2619, JN 28:385, NatCommun 5:3285), we have developed an in vitro model that appeared suited to address neuroendocrine pattern generation. This model is an organotypic culture of thick (350um) frontal slices through the anterior hypothalamic area including the supraoptic nucleus (SON) from new-born rats. In these cultures, surprisingly, the neuroendocrine magnocellular oxytocin (OT) neurons of the SON spontaneously have the same rhythmic electrical activity that they naturally display in adult lactating female rat in response to pup suckling, i.e., during the milk-ejection reflex. This rhythmic activity is typically made of high-frequency (20-50 Hz) bursts (3-8 sec) of action potentials occurring every 3-10 min in a coordinated fashion in all the OT neurons. This electrical activity allows in vivo the release of a bolus of OT in the circulation to act at the mammary gland. We thus have used these organotypic cultures to test the hypothesis that a female-specific network is entirely driving the rhythmic activity of OT neurons, analogous to the female-specific expression of rhythmic (ovulatory cycles) activity in the hypothalamo-pituitary-gonadal axis. Our results indeed suggest that a female-specific CPG network drives the pulsatility of OT neurons of the SON. This CPG is active in both sexes at birth but is subjected to postnatal apoptotic-like silencing in males during the period of brain sexual differentiation when estradiol produced from aromatized circulating testosterone sculpt brain reproductive networks. Furthermore, in accord with the above hypothesis, removing the periventricular area from the tissue slices harvested for organotypic culture completely abolished the bursting activity of OT neurons. In conclusion, the periventricular area comprises a neural network important for driving the expression of a female-specific pulsatile behaviour in neuroendocrine in OT neurons.