RT Journal Article SR Electronic T1 Cell-type heterogeneity in the zebrafish olfactory placode is generated from progenitors within preplacodal ectoderm JF bioRxiv FD Cold Spring Harbor Laboratory SP 194175 DO 10.1101/194175 A1 Raphaƫl Aguillon A1 Julie Batut A1 Arul Subramanian A1 Romain Madelaine A1 Pascale Dufourcq A1 Thomas F. Schilling A1 Patrick Blader YR 2017 UL http://biorxiv.org/content/early/2017/09/26/194175.abstract AB Vertebrate olfactory placodes consists of a variety of neuronal populations, which are thought to have distinct embryonic origins. In the zebrafish, while ciliated sensory neurons arise from preplacodal ectoderm (PPE), previous lineage tracing studies suggest that both Gonadotropin releasing hormone 3 (Gnrh3) and microvillous sensory neurons derive from cranial neural crest (CNC). We find that the expression of Islet1/2 is restricted to Gnrh3 neurons associated with the olfactory placode. Unexpectedly, however, we find no change in Islet1/2+ cell numbers in sox10 mutant embryos, calling into question their CNC origin. Lineage reconstruction based on backtracking in time-lapse confocal datasets, and confirmed by photoconversion experiments, reveals that Gnrh3 neurons derive from the anterior/medial PPE. Similarly, all of the microvillous sensory neurons we have traced arise from preplacodal progenitors. Our results suggest that rather than originating from separate ectodermal populations, cell-type heterogeneity is generated from overlapping pools of progenitors within the preplacodal ectoderm.