An analysis of the cells derived from the olfactory placode and its possibl correlation of the migrating LHRH neurons.

点击翻译按钮获取中文摘要

The actual migration of LHRH neurons from the nasal epithelium to the forebrain was demonstrated in the chick embryo using fluorescent dye-labeling. There were a number of labeled cells which did not co-express LHRH.These results suggest that some non-LHRH neurons in the forebrain are of olfactory placodal origin. In order to identify the other cell types migrating into the forebrain together with LHRH neurons, the tissue distribution of somatostatin (SST) immunoreactivity was studied in the nasal and forebain region in the chick embryo. On embryonic day (ED) 3.5, SST immunoreactive (-ir) cells and -ir fibers appeared in the olfactory epithelium and olfactory nerve bundles. At ED6-8, one component of the SST-ir fibers was found to separate from the olfactory nerve and it entered the medial forebrain surface. During this same period, a few SST-ir cells were observed in the medial forebrain adjacent to the SST-ir fibers. SST immunoreactivity in the nasal and forebrain areas was most striking at ED5-8 but it virtually disappeared by the day of hatching. These results indicate that the expression of SST in the nasal and forebrain region is transient in the chick embryo. Since the SST-ir cells did not co-express LHRH, it appears that SST-ir cells belong to a different cell population from LHRH neurons. However, a close relationship exist between SST-ir neural elements and LHRH neurons. This may play a role in development of LHRH neurons. Additionally, the appearance of the SST-ir cells in the forebrain at ED6-8 suggest their migraiton from the nasal region.