Fig. 4.

Sox2 is preferentially expressed in undifferentiated Schwann cells. Analysis of Sox2 expression by quantitative RT-PCR during Schwann cell development (A), after nerve crush injury (B), in P14 Egr2^Lo/Lo CHN Schwann cells (C), and in immature nonmyelinating cultured Schwann cells (D) indicate elevated Sox2 expression in undifferentiated Schwann cells. Sox2 protein (E) is present at higher levels in P14 Egr2^Lo/Lo CHN nerves than in the age-matched myelinated wild-type or Egr2^+/Lo nerves. In contrast to wild-type nerves (F), Egr2^Lo/Lo nerves (G) have increased Sox2 staining (green nuclei) along with increased L1 staining (red), a marker of undifferentiated Schwann cells. In comparison to uninjured adult P56 nerve (H), nerve 4 days after crush (I) demonstrated diminished neurofilament staining (red), and an increased number of Sox2-positive nuclei (green). Additionally, the intact nerve (J) showed minimal L1 (red) and Sox2 (green) staining, whereas nerve 4 days after crush (K) displayed increased L1 (red) and Sox2 (green) staining.