Extended Data Fig. 7: Gonadal supporting PAX8+ cells define gonadal boundaries.

a, Spatial mapping of somatic cell types from the scRNA-seq human dataset to three consecutive spatial transcriptomics slides of a 14 PCW testis using cell2location. Estimated abundance for cell types (colour intensity) contributed by each cell population to each spot (colour) shown over the H&E image; n = 3. Scale bars = 1 mm. b, UMAP (uniform manifold approximation and projection) showing mesothelial, first wave supporting and epithelial cells in human first trimester (left) and mouse embryonic day (E) E10.5-E12.5 (right) scRNA-seq data labelled by cell type, location of the tissue, sex, donor or sample and post-conceptional weeks (PCW) or stage. c, Dot plot showing the variance-scaled, log-transformed expression of genes characteristic of the mesothelial, supporting and epithelial subpopulations in human first trimester (top) and mouse E10.5-E12.5 (bottom) scRNA-seq data. d, High-resolution large-area imaging of representative gonadal section (sagittal) of a human fetal testis (7PCW, Carnegie Stage CS17) with intensity proportional to smFISH signal for GATA4 (green, gonadal), PAX8 (red, sPAX8 population) and GATA2 (cyan, extragonadal); n = 5. This sample is also shown in Extended Data Fig. 3c. e, High-resolution large-area imaging of a representative section of a mouse fetal ovary (E13.5) with intensity proportional to smFISH signal for Lgr5 (yellow, cortical pre-granulosa), Pax8 (red, sPAX8), Hmgcs2 (green, medullary pre-granulosa) and Gng13 (magenta, cortical pre-granulosa); n = 2. f, High-resolution large-area imaging of representative sections of three human fetal testes (sagittal late 8, transverse 11 and transverse 12 PCW; n = 3) with intensity proportional to smFISH signal for PAX8 (yellow, sPAX8 population), NR5A1 (cyan, interstitial Fetal Leydig), EPCAM (red, low in supporting cells, high in epithelial cells of the reproductive tubules) and KLK11 (green; coelomic epithelium). g, High-resolution large-area imaging of representative sections of two human fetal ovaries (9 and 11 PCW; n = 2) with intensity proportional to smFISH signal for the same panel in “f”. h, (left) Dot plot showing the scaled log-transformed expression of upregulated genes coding for sPAX8 ligands or receptor proteins in the supporting testis cells. (right) Dot plots showing the scaled log-transformed expression of genes coding for cognate ligand or receptor proteins in the supporting epithelial, endothelial and germ cells. Interacting partners (i.e., with binding specificity) are linked with a matching symbol. CoelEpi = coelomic epithelium; E = embryonic day; Epi = epithelial; ESGC = early supporting gonadal cells; FGC = fetal germ cells; Gi = gonadal interstitial; M = mesonephros; PCW = post-conceptional week; PGC = primordial germ cells; preGC = pre-granulosa cells; sPAX8 = supporting PAX8; Ti = testicular interstitial. For all smFISH panels, unless otherwise specified, white dashed rectangles highlight gonadal regions magnified; scale bars = 100 µm and 10 µm in magnified regions.