This study deals with the distribution and morphological study of the neurons with the neuropeptide Y (NPY) in developing chick brain. The developing brains of Korean native chicks at embryonic days 8 (E8), E10, E12, E14, E16, E18, and E20 were used. The chicks were perfused with 4% paraformaldehyde through the left ventricle and aorta. The brains were removed and transferred into 30% sucrose, and then cut in a cryostat into 60㎛ in thickness. The sections were immunostained with free-floating and avidin-biotin complex (ABC) methods.
The numerous neurons with NPY were first observed in nucleus rotundus of diencephalon at E8. In particular, neurons in nucleus rotundus had the well-developed processes. At E12, the neurons with NPY were distributed widely in diencephalon; nucleus septalis lateralis, medialis, nucleus magnocelluairs preopticus dorsalis, medialis, ventralis, nucleus preopticus medialis, nucleus dorsolateralis anterior thalami pars magnocellularis, and nucleus paraventricularis magnocellularis (paraventricular nucleus) except nucleus rotundus. From E12 to E20, positive neurons were oval-shaped, changed gradually into the spherical- and multipolar-shaped. The shapes of processes were also omnidirectional and the number of those were less than in telencephalon. As the chicks developed, the morphology of neurons with NPY showed the tendency to increase in their sizes and numbers.
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