Fig. 2. C6st1 mRNA expression is upregulated in Schwann cells emigrating from sciatic nerve explants but not in Schwann cells at confluence. Schwann cells emigrating from explants of sciatic nerves (adult rats) are compared with confluent cultures of purified Schwann cells. (A) Phase-contrast (A₁) and immunofluorescence (A₂) views of emigrating Schwann cells doubly immunopositive for the S100 and CS56 epitopes. Emigrating Schwann cells reveal colocalisation of fluorescence in situ hybridisation signal for C6st1 mRNA (C6ST) and immunofluorescence for either S100 (A₃) or GFAP (A₄). The GFAP-positive migrating Schwann cells show negligible hybridisation signal when tested with the sense riboprobe (A₅). (B) Phase-contrast (B₁) and combined hybridisation- and immunofluorescence (B₂) views of confluent cultures of purified Schwann cells, showing insignificant expression of C6st1 mRNA in spindle-shaped, bipolar, S100-positive Schwann cells. Similarly, these Schwann cells were S100-positive but CS56-negative, as observed with double immunofluorescence (B₃). (C) Histogram showing prevalence of C6ST-expressing, S100-positive Schwann cells (SC) in the sciatic nerve (SN) explant over those in confluent cultures of purified Schwann cells (P<0.001). Total Schwann cell counts are listed under the histogram. Error bars represent s.e.m. of three independent experiments. Bars, 25 µm (B, upper panels in A); 50 µm (lower panels in A).