Olfactory Schwann cells are derived from precursor cells in the olfactory epithelium

In this morphological and immunohistochemical study we show that olfactory schwann cells (OSC) are derived from precursor cells residing in the olfactory epithelium. During development, they migrate out of the epithelium and extend processes to ensheath the olfactory axons. Olfactory mucosa from E14 rat embryos and juvenile rats were treated with trypsin-pancreatin to remove the underlying connective tissue. The epithelial explant was then maintained for two days in culture, during which cells migrated out from the explant. Among them were spindly bipolar cells which were identified as OSC by their positive immunoreaction for glial fibrillary acidic protein, ultrastructure, and association with growing axons. Axonal growth was significantly more profuse in the embryonic explants, in which the polarity of the OSC was oriented parallel with the axons. Ultrastructural observations showed that ensheathment of the bundles of axons resembled those in vivo.