FIG 6 .

B. pseudomallei enters the central nervous system (CNS) via open channels. (A) Schematic sagittal view of the nasal cavity and olfactory system. The trigeminal nerve (red) is represented in panel B; the yellow boxed area is represented in panels C to E. (B) Some trigeminal nerve axons (blue) surrounded by Schwann cells degenerate as a result of the infection, and B. pseudomallei (green) migrates through the empty Schwann cell canals. (C) In healthy animals, primary olfactory neurons (blue) reside in the olfactory epithelium (OE) and project axons (blue lines) in nerve bundles through the cribriform plate (CP) into the olfactory bulb (OB) within the central nervous system. OECs (red) surround the nerve bundles. (D) Exposure to B. pseudomallei (green rods) results in neurons degrading (dark blue ovals) in some regions of the epithelium; the loss of the neuron cell bodies (brown ovals) from the epithelium leads to the degradation of their axons (dashed lines); OECs remain intact. (E) After the epithelium is sloughed off into the nasal cavity, the bacteria penetrate the remaining layers of the mucosa and migrate along the open channels left by the degraded axons and thereby enter the central nervous system.