Size regulation of dorsal root ganglia (DRG) in developing axolotls with a deficiency or oversupply of neural crest material

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The neural crest (NC) is a key structure in vertebrate embryos that gives rise to various important derivatives such as pigment cells, the viscerocranial skeleton, or ganglia and glia of the peripheral nervous system. We investigate the size regulation of NC-derived dorsal root ganglia (DRG) at two different timepoints during the development of the axolotl (Ambystoma mexicanum) following an experimental under- and oversupply with NC material. The axolotl is known for its regenerative capacity. It can regenerate missing structures such as limb, tail or the spinal cord and is therefore predestined for studies on tissue repair. In our main experiments we remove both neural folds of a white (d/d) host neurula and a) replace its right neural fold with one GFP+ labeled fold containing NC cells or b) implant four GFP+ neural folds, two for each extirpated fold. In both cases (a+b) we determine the size of GFP+ DRGs on cryosections through three defined anterior trunk segments in an early time group (developing larvae, 10 mm) and a later timegroup (juveniles, 4-8 cm) which are stained with anti-GFAP and Dapi. Our aim is to find out whether the size of DRGs can be up- or downregulated to normal size in larvae or juveniles when one orfourGFP+folds are present, respectively.