Recognizing that osmotic pressure is a principal factor controlling antidiuresis, Verney introduced the term 'osmoreceptor' to designate the mysterious cerebral structures that regulate vasopressin release from the posterior pituitary. While hormone secretion from the neurohypophysis is influenced by synaptic inputs from other osmoresponsive neurons, magnocellular neurosecretory cells currently provide our most comprehensive model of signal detection in an osmoreceptor.