Sox2 expression in the myenteric plexus in the caecum of postnatal and adult mouse

The enteric nervous system originates from the enteric neural crest stem cells and a subset of Schwann cell precursors, which colonize the intestine at embryonic stages. Enteric neural crest stem cells differentiate into glial cells and neurons, whereas the Schwann cell precursor subset differentiates into neurons. The expression of Sox2 was currently described in enteric nervous system progenitor and glial cells from embryonic to adult stage.

In this study, the expression of Sox2 in the myenteric plexus of the mouse caecum was investigated. The caecum is an important site of fermentation and harbors a huge number and variety of intestinal bacteria. These permanent environmental stimuli should be mirrored in the phenotype of the glial cells, neurons and their progenitors. The Sox2 expression was analysed in combination with glial and neuronal markers by immunofluorescence stainings at the postnatal and adult stage in mice.

As expected the expression of Sox2 was predominantly found in glial cells that expressed the common glial markers S100 or GFAP. Moreover, there were also Sox2 expressing cells in the myenteric plexus with a neuronal morphology (nSox2). The nSox2 cells expressed the pan neuronal markers PGP9.5 and HuC/D. Moreover, there was also a frequent expression of different neuronal subtype markers such as calretinin or calbindin in nSox2 cells. A glia-neuron intermediate cell type was excluded due to the fact that nSox2 cells expressed neither S100 nor GFAP. A similar absolute amount of nSox2 cells was found in postnatal and adult mice. Roughly 80% of the myenteric ganglia contained nSox2 cells at both ages.

In summary, Sox2 is expressed in both enteric glia and neurons in the postnatal and adult caecum. Hence, Sox2 is most probably not associated with self-renewal in postmitotic enteric neurons and exerts other functions such as cell survival.