Figure 1.

All three major RALDH enzymes are differentially expressed in the adult OM. A: Low-power image of RALDH-1 expression. Note that RALDH-1 is found in the Sus cells in the ventral and lateral epithelium, and that the boundary is sharply defined. D–F: Insets from (A) show that in the dorsomedial region (D) RALDH-1 is absent from the superficial mesenchyme, but it is present in the OECs in the olfactory nerve fascicles (on). The boundary between dorsal and ventral is sharply delimited (E), and in the ventrolateral region RALDH-1 staining is apparent in the OECs and the Sus cells (F). B: Low-power image of RALDH-2 expression. G–I: Insets from (B) show that like RALDH-1, RALDH-2 is found only in the deep mesenchyme in the dorsomedial region (G). The boundary matches that of RALDH-1 (H). In the ventrolateral region, RALDH-2 is expressed both by cells in the superficial mesenchyme and the deep mesenchyme (I). C: Low-power image of RALDH-3 expression. J–L: Insets from (C) show that in the dorsomedial region RALDH-3 is not present (J). The boundary between dorsal and ventral is sharply delimited (K), and in the ventrolateral region RALDH-3 staining is apparent in cells directly beneath the basement membrane (L). In these images arrowheads mark the basal lamina. Scale bars = 50 μm in A–C; 20 μm in J–L.