Extended data figure 7: Analysis of gene expression in lamprey sympathetic neurons.

(a) Representative image of a wild-caught lamprey ammocete used for selection of trunk sympathetic neurons. Scale bar=1cm. (b and c) Immunohistochemical detection of TH (teal) in transverse sections through ammocete trunks. DAPI is shown in white. Yellow box indicates the site of the sympathetic chain neurons. SC=spinal cord, NC=notochord. Scale bars=250μm (a) and 10μm (b). n=4 ammocetes across three independent replicates. (d and e) GO analyses of Metabolites and Cell Compartment for TH⁺ neurons. Analyses are performed using the top 500 significantly upregulated transcripts with an enrichment cutoff of 1.5 log₂(Fold Change). p-values are determined using Fisher’s exact test. (f) Immunohistochemical detection of DBH (teal) at T28. Punctate expression is consistent with vesicular localization of DBH protein. Scale bar=20μm. n=6 embryos across three independent replicates.