(A) The list of 295 entries annotated as testis-expressed in the Eurexpress database were compared to 130 interstitial cell-expressed genes from a microarray of sorted cells at 13.5 dpc (Jameson et. al., 2012). 9 genes were represented in both sources (see Supp Table 2). (C) Among these genes, 4 known interstitial/Leydig cell marker genes were identified: Cyp11a1, Prlr, Star and Tacr3. (C) high quality in situ hybridization images were available for 5 of the 9 overlapping interstitial genes: Clca1, Cxcl12, Itga9, Nrg1 and Sostdc1. (D) 11 genes were represented in both the Leydig cell microarray and the Eurexpress database (see Supp Table 2); (E) high quality in situ hybridization images were available for 8 genes: Fads1, Gramd1b, Hsd17b7, Prkar2b, Ren1, Scarb1, Sct and Stc1. . The testis region is demarcated by a dashed line. a: adrenal; k: kidney; m: mesonephros. Scale bar: 0.5 mm.