Cellular diversity of the developing chick trigeminal ganglion at single-cell resolution

The trigeminal ganglion (TG) integrates sensory input from the face and jaw and is derived from two embryonic cell populations: neural crest and cranial placode. These populations interact during TG development to coordinate specification, differentiation, and organization, but the molecular characteristics of the heterogeneous cell populations within the developing TG remain poorly defined.

We performed single-cell RNA-sequencing (scRNA-seq) of chick TG at HH17, generating a high-resolution dataset of ~87,000 cells representing diverse neuronal and non-neuronal populations. Subclustering and RNA velocity analysis of Isl1⁺ neuroblasts resolved distinct developmental trajectories associated with neural crest- and cranial placode-derived populations converging toward neuronal differentiation. A Sox10⁺ neural crest-associated population progressively acquired neuronal characteristics, while a distinct placode-associated trajectory exhibited loss of epithelial gene expression during neuronal maturation. We additionally identified lineage-enriched long non-coding RNAs (lncRNAs), including MIR137HG, which was strongly enriched in Isl1⁺ neuroblasts and spatially validated across TG development.

Our study provides a single-cell atlas of the developing chick TG that resolves transcriptional heterogeneity and developmental states within its neural crest- and placode-derived populations. These data identify candidate molecular signatures associated with sensory neuronal differentiation and provide a resource for investigating the mechanisms governing trigeminal gangliogenesis.