Although secretory immunoglobulin A (sIgA) is a very important substance in the defence mechanism of respiratory and nasal
mucosa, research on its expression in the olfactory mucosa and differences according to development is limited. Therefore, we
planned to uncover the sites of sIgA expression in the olfactory mucosa as well as changes in its expression depending on the
developmental progress of mice. Our results showed the expression of sIgA in the mucus layer, the Bowman’s gland, some of
the blood cells and secretory ducts of the olfactory mucosa, and these findings were relatively consistent from gestational day
15 through to the adult stage. The different findings between the gestational day 15 specimens and others include a positive reaction in the Bowman’s gland for gestational day 15 specimens. Therefore, we would like to predict with caution that the Immunologic regulation of mice should be completed at least after the 15th gestational day