Schwann-like macroglia in adult rat brain.

Olfactory ensheathing cells (OECs) share properties with astrocytes and Schwann cells. This study was designed to test the hypothesis that glia with properties similar to those exhibited by OECs might be present in brain areas other than the olfactory bulb. We found tanycytes and pituicytes to express a distinctive set of immunological markers in common with OECs and nonmyelinating Schwann cells, namely low-affinity neurotrophin receptor (p75NTR), O4 antigen, estrogen receptor-alpha type, and insulin-like growth factor 1 (IGF-1). The two glial types could be cultured from adult hypothalamus and neurohypophysis, respectively, using the methods developed for olfactory OECs. Both glial types displayed morphologies reminiscent of Schwann cells, in primary culture. Schwann-like central glia presented a preferred growth substrate for dorsal root ganglion neurites and, when making intimate contacts with them, manifested a myelinating phenotype. These combined properties define a type of CNS macroglia that would not fit within conventional central glia types.