Cyto-, dendro- and fibro-architectonic studies on the chicken hypothalamus.

Based on the chicken hypothalamic analysis using the Nissl, Golgi-Cox and silver staining methods, a first attempt to make the cyto-, dendro- and fibro-architectonic atlases of the frontal planes at the same level was performed. In the preparations stained with Nissl method, the hypothalamus was subdivisible basically into the preoptic, rostral and caudal hypothalamic regions, each of which was composed of medial and lateral parts respectively. A well-defined boundaries between the preoptic and rostral hypothalamic regions was decided at the level of the rostral margin of the commissura rostralis. On the other hand, the one between the rostral and caudal hypothalamic regions was also visible between the nucleus hypothalamicus caudalis medialis and the nucleus hypothalamicus inferior. However, no distinct borderlines between two hypothalamic nuclei, as shown in the preparations using the silver method, were designated, when the distribution of the dendrites of nerve cells was used as criteria for analysis. Furthermore, the nerve cells of all hypothalamic nuclei showed almost the same morphological patterns: namely the nerve cells were generally triangular, round or spindle shape and they had a few long relatively straight fine dendrites leaving the cell body in all directions and having very fine dendritic spines.