Netherlands Central Institute for Brain Research, Ijdijk 28, Amsterdam-0, The Netherlands
(Received 3 July 1975)
The 'classical' view on the distribution of oxytocin and vasopressin producing cells suggests that the paraventricular nucleus (PVN) is predominantly or entirely responsible for oxytocin production and the supraoptic nucleus (SON) synthesizes mainly vasopressin. However, recent hormone assays and electrophysiological studies indicate the presence of each hormone in both nuclei (for references see Burford, Dyball, Moss & Pickering, 1974). We report an immunofluorescence study in the SON and the magnocellular part of the PVN (Bodian & Maren, 1951) using antibodies to oxytocin (produced in our laboratory) and to vasopressin (produced by Drs Hollemans, Schellekens and Touber), purified by absorption with arginine-vasopressin and oxytocin respectively (Swaab & Pool, 1975).
Frontal cryostat serial sections of glyoxal-prefixed hypothalami from five male Wistar rats weighing 200 g were studied. Out of each group of six sections, the first was