Ontogeny of the bovine neurohypophyseal hormone precursors. Foetal neurohormones and neurophysins.

Neurohypophyseal hormones are fragments of precursor proteins that include specific neurophysins and are processed during axonal transport. Neurohormones and neurophysins purified from 7-9 month old bovine foetuses have been characterized by amino acid analysis and partial amino acid sequences. Oxytocin and arginine vasopressin, on one hand, and VLDV-neurophysin and MSEL-neurophysin, on the other, are identical to products previously characterized in the adult. Whereas oxytocin and vasopressin genes seem to be expressed at the same rates in the adult, as judged by the amounts of their peptide products in neurohypophysis, in the late foetus the vasopressin gene appears to be roughly three times more active than the oxytocin gene.