Characterization of a RFamide-positive subset of ganglionic cells in the hydrozoan planular nerve net.
The complexity of the hydrozoan planular nervous system was examined. Using a whole-mount technique with indirect immunofluorescence, the spatial pattern of ganglionic cells showing RFamide-like immunoreactivity was visualized. RFamide antiserum bound a subset of ganglionic cells in the anterior and upper middle regions of the planula and a few ganglionic cells in the upper tail region. Labeled cells consisted of bipolar and multipolar neurons. Stained processes from these cells formed a three-dimensional nerve net that followed the contour of the mesoglea; such fibers were striking in terms of their large numbers, long lengths, and organization into distinct bundles. Labeled fibers were seen to contact other ganglionic cells, sensory cells, epithelio-muscle cells, the mesoglea, and the outside free surface. All stained cell bodies and fibers were found in the ectoderm. Using the same technique the reappearance of RFamide-positive ganglionic cells in epithelial tissue of chimeric grafts of planulae was observed. Interstitial cells capable of forming RFamide-positive ganglionic cells underwent extensive anterior-posterior migrations in the grafts, moved into the epithelial tissue, and differentiated into RFamide-positive ganglionic cells. Stained repopulated ganglionic cells always formed in the same position in the epithelial tissue as was observed in control planulae suggesting that the expression of RFamide-like substances may be position dependent in the planula.
Department of Biological Sciences, University of Notre Dame, IN 46556.
V J
VJ
Martin
D000818:Animals; D003063:Cnidaria / Q000033:anatomy & histology* / Q000378:metabolism; D004847:Epithelial Cells; D004848:Epithelium / Q000737:chemistry; D005260:Female; D005724:Ganglia / Q000737:chemistry* / Q000166:cytology*; D007106:Immune Sera; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000737:chemistry; D009479:Neuropeptides / Q000032:analysis* / Q000378:metabolism
D007106:Immune Sera; D009479:Neuropeptides; C058047:arginylphenylalaninamide