Histology staining
The epithelial specimens underwent standard histological techniques. The
samples were dehydrated using a series of ethanol concentrations and
then cleared with xylene. Following infiltration and embedding in
paraffin wax (melting point 56-58℃), they were sectioned using a rotary
microtome (PR-50; Yamato Kohki Industrial Co., Ltd, Saitama, Japan) into
slices measuring 4-6 μm. These sections were spread out on warm water,
carefully transferred onto glass slides, and subsequently dried in an
incubator at 60℃ for 30 minutes. During the staining process, they were
sequentially immersed in deparaffinization solution, hydration medium,
and stain solution. Following mounting, the epithelial samples were
examined and photographed using a digital microscope (VHX-7000; Keyence,
Osaka, Japan). We evaluated whether these epithelial tissues qualified
as olfactory epithelium based on the criteria proposed by Farnkopf et
al. (2022): epithelium constructed of basal cells, supporting cells, and
olfactory sensory neurons; the presence of Bowman’s glands; the absence
of goblet cells; and the distance between the apical surface and the
nuclei of the supporting cells.