Electron microscopic depiction of the olfactory epithelium of a young (32 d) NPC1^−/− animal.

Some of the cells are exemplarily colored. The OE consists 1) of olfactory receptor neurons in the middle portion of the OE (O, green) with thin apical processes extending with knob-like structures into the mucous layer, 2) supporting cells, the nuclei of which lie in the upper third, and with basal footplates (S, yellow) above the basal membrane (magenta line), and 3) basal cells (B). There are many irregular, myelin-like inclusions within most of the cells (arrows). Most of these autophagosomes occur in subnuclear portions of supporting cells, but also, to a lesser degree, in perinuclear locations of ORN. Apical processes of ORN are not affected (see also Fig. 7). Singular, huge accumulations of myelin-like deposits are occasionally seen near the basal membrane, most likely corresponding to Gal-3 – and CatD-positive macrophages (M, red; see also Figs. 4,5). BG, Bowman glands of the lamina propria.