POSTERIOR PITUITARY OF THE NEWBORN MARSUPIAL POSSUM, TRICHOSURUS-VULPECULA

The fetal anterior pituitary-adrenal axis is thought to be involved in the initiation of birth in both eutherian and marsupial mammals. Litt le is known about the structure and function of the posterior pituitar y at birth in the marsupial. Immunocytochemistry, high pressure liquid chromatography, and radioimmunoassay were used to identify vasopressi n and mesotocin in the posterior pituitary of a newborn marsupial, the brushtail possum, Trichosurus vulpecula. The concentrations of vasopr essin and mesotocin in the head of the newborn possum were 0.34 and 0. 28 ng, respectively. The concentration of vasopressin was always great er than that of mesotocin, and the amounts of neuropeptides present in the head increased as the possum developed. (C) 1993 Wiley-Liss, Inc.