Coordinated development of the peripheral and central olfactory system in zebrafish Danio Rerio / Jorge Eduardo Torres Paz.

Magíster en Ciencias Biológicas. Mención Neurociencia.

The main components of the peripheral nervous system (PNS) develop from sensory placodes, which form at the neural plate. Although all placodes produce different cell tpes, it is assumed that they have a similar pattern of development: they are induced by the neuroectoderm from the adjacent ectoderm. Fate maps in zebrafish showed that precursors of both central olfactory system (COS) and peripheral olfactory system (POS) lie next to each other at the end of gastrulation, long before placodes arise (late somitogenesis). We have analyzed the developmental relationship of COS and POS during morphogenesis, taking advantage of the transparency of the transparency of zebrafish embryos and availability of transgenic lines to perform imaging in live and fixed animals. We show that precursors of COS and POS are located in a continuous domain that expresses the transcription factor Dlx3b. The physical separation of central and peripheral olfactory precursors starts with the formation of a basal lamina at early somitogenesis and continues with the anterior migration of the cranial neural crest (CNC) coincident with the appearance of a second basal lamina (at the 20 somite stage). During morphogenesis, precursors of COS and POS show similar morphogenetic movements which are differents from those of visual system precursors. Gene knockdown of transcription factors dlx3b and dlx4b (dlx3b/4b) show that, although the separation between COS and POS occured normally in morphants, there is a reduction in the size of the developing POS, apparently at the expense of COS overgrowth.