Fig. 4. Neurodegenerative and inflammatory changes in PITPα^−/− spinal cord.

A, complete spinal cord sections were generated by reconstructing images from 2-μm-thick, epoxy resin-embedded sections of PITPα^+/+ stained with toluidine blue O (left, number of images n = 30) and PITPα^−/− spinal cord (right, n = 22). Bars are 0.15 mm. B, images from the ventral interface between gray and white matter (GM/WM interface) of cervical spinal cord sections. Top panels, representative images of PITPα^+/+ motor neuron cell bodies (left, open arrows) and abnormally dark staining PITPα^−/− motor neuron cell bodies (right, dark arrows) are indicated. Bars are as follows: left, 50 μm; right, 100 μm. WM regions are indicated. Bottom panels, additional images from GM/WM interface of PITPα^−/− cervical spinal cord are shown. Characteristic neurodegenerative symptoms include highly vacuolated cells (center panel, solid arrow), dark cells (right panel, solid arrows), and abnormally lightly stained cells without discrete intracellular structure (right panel, *). Bars are as follows: left, 100 μm; center, 50 μm; right, 20 μm. C, inflammatory cells in PITPα^−/− thoracic spinal cord. Left panel, mast cell (MC) and capillary lumen (C) are indicated. Right panel, macrophage (MF) and capillary lumen (C) are indicated. Bars are as follows: left, 20 μm; right, 5 μm. D, electron micrographs of myelin from the WM/GM interface of PITPα^+/+ (left) and PITPα^−/− spinal cord (center). Examples of myelinated axons are indicated by arrows. Right panel, cells that may be remodeling myelin are present in large numbers in PITPα^−/− mice and an example is indicated (*). Bars are as follows: left, 15 μm; center, 10 μm; right, 6 μm.