DEVELOPMENT AND MATURATION OF NEUROENDOCR INE PATHWAYS OF THE HYPOTHALAMONEUROHYPOPHYSEAL SYSTEM - THE CHICKEN-EMBRYO AS MODEL

Title of the paper: Development and maturation of neuroendocrine pathw ays of the hypothalamo-neurohypophysial system - The chicken embryo as model. The hypothalamus is the central integrative structure for the neuroendocrine regulation of water and electrolyte balance. Despite ma ny different endocrine and other factors the neurohormone Argininte Va sotocin (AVT) plays an important role. In this review we described dev elopmental and maturational aspects of the AVT synthesezing hypothalam o-neurohypophysial system. The chicken embryo and the newly hatched ch icken were used for these in vivo and in vitro investigations. Althoug h the onset of AVT gene expression and peptide synthesis is as early a s around day 6 of embryonal life, osmoregulatory function may not occu r before the end of the second week of incubation. Rapid maturational processes during the last week of embryonal development lead to a ''cl ose-to-mature'' response of the AVT secretory system to physiological (osmotic) stimulation in the one-day-old chicken.