The olfactory placodes of the zebrafish form by convergence of cellular fields at the edge of the neural plate.
The primary olfactory sensory system is part of the PNS that develops from ectodermal placodes. Several cell types, including sensory neurons and support cells, differentiate within the olfactory placode to form the mature olfactory organ. The olfactory placodes are thought to arise from lateral regions of the anterior neural plate, which separate from the plate through differential cell movements. We determined the origins of the olfactory placodes in zebrafish by labeling cells along the anterior-lateral edge of the neural plate at times preceding the formation of the olfactory placodes and examining the later fates of the labeled cells. Surprisingly, we found that the olfactory placode arises from a field of cells, not from a discrete region of the anterior neural plate. This field extends posteriorly to the anterior limits of cranial neural crest and is bordered medially by telencephalic precursors. Cells giving rise to progeny in both the olfactory organ and telencephalon express the distal-less 3 gene. Furthermore, we found no localized pockets of cell division in the anterior-lateral neural plate cells preceding the appearance of the olfactory placode. We suggest that the olfactory placodes arise by anterior convergence of a field of lateral neural plate cells, rather than by localized separation and proliferation of a discrete group of cells.
Field of Genetics and Development, Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA. kew13@cornell.edu
K E
KE
Whitlock
M
M
Westerfield
D000818:Animals; D002455:Cell Division; D019070:Cell Lineage; D004268:DNA-Binding Proteins / Q000235:genetics; D051858:Forkhead Transcription Factors; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000235:genetics; D008938:Mitosis; D009432:Neural Crest / Q000196:embryology* / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism; D009832:Olfactory Nerve / Q000196:embryology* / Q000378:metabolism; D016548:Prosencephalon / Q000196:embryology* / Q000378:metabolism; D013687:Telencephalon / Q000196:embryology / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics; D015027:Zebrafish / Q000196:embryology*; D029961:Zebrafish Proteins
D004268:DNA-Binding Proteins; C088334:Distal-less homeobox proteins; D051858:Forkhead Transcription Factors; D018398:Homeodomain Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; C491002:foxd3 protein, zebrafish