Close association of olfactory placode precursors and cranial neural crest cells does not predestine cell mixing

• Published in: Developmental dynamics 2012-07, Vol.241 (7), p.1143-1154
• Main Authors: Harden, Maegan V., Pereiro, Luisa, Ramialison, Mirana, Wittbrodt, Jochen, Prasad, Megana K., McCallion, Andrew S., Whitlock, Kathleen E.
• Format: Article
• Language: English
• Subjects: Animals; Animals, Genetically Modified; Danio rerio; dlx3b; Embryo, Nonmammalian - metabolism; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Immunohistochemistry; In Situ Hybridization; Neural Crest - cytology; Neural Crest - metabolism; Olfactory Pathways - cytology; Olfactory Pathways - metabolism; six4b; sox10; SOXE Transcription Factors - genetics; SOXE Transcription Factors - metabolism; Trans-Activators - genetics; Trans-Activators - metabolism; Zebrafish; Zebrafish Proteins - genetics; Zebrafish Proteins - metabolism
• ISSN: 1058-8388; 1097-0177
• DOI: 10.1002/dvdy.23797

Vertebrate sensory organs originate from both cranial neural crest cells (CNCCs) and placodes. Previously, we have shown that the olfactory placode (OP) forms from a large field of cells extending caudally to the premigratory neural crest domain, and that OPs form through cell movements and not cell division. Concurrent with OP formation, CNCCs migrate rostrally to populate the frontal mass. However, little is known about the interactions between CNCCs and the placodes that form the olfactory sensory system. Previous reports suggest that the OP can generate cell types more typical of neural crest lineages such as neuroendocrine cells and glia, thus marking the OP as an unusual sensory placode. One possible explanation for this exception is that the neural crest origin of glia and neurons has been overlooked due to the intimate association of these two fields during migration. Using molecular markers and live imaging, we followed the development of OP precursors and of dorsally migrating CNCCs in zebrafish embryos. We generated a six4b:mCherry line (OP precursors) that, with a sox10:EGFP line (CNCCs), was used to follow cell migration. Our analyses showed that CNCCs associate with and eventually surround the forming OP with limited cell mixing occurring during this process. Developmental Dynamics 241:1143–1154, 2012. © 2012 Wiley Periodicals, Inc. Key findings: The six4b:mCherry line expresses mCherry in the forming olfactory placodes. mCherry expressing cells move caudally, away from the anterior midline, to form the olfactory placodes. Sox10:GFP positive cranial neural crest cells migrate rostrally to surround the forming olfactory placodes. Little cell‐mixing is observed during the migation of Six4b:mCherry and Sox10:GFP expressing cells.