The neurohypophysial hormones and genes in human, fugu and coelacanth. (A) Structure of the neurohypophysial preprohormones. VP, vasopressin; VT, vasotocin; OT, oxytocin and IT, isotocin. (B) Organization of neurohypophysial hormone genes in human, fugu and coelacanth. Genes are represented by arrows. Only the neurohypophysial genes are labeled. The coelacanth genes were characterized in this study.