Fig. 1: Single-cell transcriptome analysis of SCs identifies SEMA3B as a potential molecule regulating RB assembly.

a Representative TEM images of the mouse sciatic nerve showing the spatiotemporal assembly of RB. nmSC lamellipodia either ensheath axons (closed arrowheads) or separate adherent axons (open arrowheads). Asterisks and circles indicate axons entirely or partially wrapped by nmSC lamellipodia, respectively. Data are representative of 3 mice across all developmental stages. Abbreviations: n nucleus, mA, myelinated axon. b Quantitative assessment of RB assembly progression, as measured by the Remark Bundle Maturity (RBM) Index. Data are presented as mean ± SEM. Sample size: n = 21/5 (number of RBs/number of mice), 23/4, 18/5, 27/6, 26/5, 28/5, and 16/4 for P0, P7, P14, P21, P28, P60, and P120, respectively. c UMAP plot illustrating the diversity of cell subtypes. d UMAP plot illustrating the cell-cycle phase. e UMAP plot illustrating the pseudotime assigned to each SC. f UMAP plots illustrating the expression of marker genes for SCPs (Mki67), iSCs (Ednrb), mSCs (Ncmap), and nmSCs (Scn7a). g-i FISH on cryosections of the mouse sciatic nerve showing indicated gene/protein expression in SOX10⁺ SC subsets. Arrowheads and arrows indicate MKI67⁺Ednrb⁺ SCPs and MKI67^-Ednrb⁺ iSCs in (g), Ednrb⁺Scn7a⁺ iSCs and Ednrb^-Scn7a⁺ nmSCs in (h), Ncmap⁺Scn7a^- mSCs and Ncmap^-Scn7a⁺ nmSCs in (i), respectively. Data are representative of 3 mice. j Relative proportions of SC lineages at each stage. k scFates-based pseudotemporal UMAP analysis of SC lineage progression. l UMAP plot indicating SC subtype diversity. m Schematic of genetic programs and potential time frames for RB assembly and myelination underlying SC development. n Volcano plot for differentiated expressed genes (DEGs) in SCs compared to non-SCs. DEGs were identified using a two-tailed Wald test with Benjamini-Hochberg adjustment for multiple comparisons (FDR-adjusted p value < 0.05 and |log₂ fold change|> 0.25). o Dot plot of the 15 most significantly over-represented KEGG pathways in SCs. Pathway enrichment was analyzed by a two-tailed Wald test with Benjamini-Hochberg correction (FDR-adjusted p value < 0.05 and |log₂ fold change|> 0.25). p Dot plot showing relative expression of selected genes in the axon guidance pathway across different SC types and ages. Source data are provided as a Source Data file.