PROTEIN GENE-PRODUCT 9.5-LIKE AND CALBINDIN-LIKE IMMUNOREACTIVITY IN THE NASAL RESPIRATORY MUCOSA OF PERINATAL HUMANS

Background: Protein gene product 9.5 (PGP) and calbindin-D28k (calbind in) are neuroendocrine markers that have been localized to neuroendocr ine cells in the developing tracheobronchial epithelium. Neuroendocrin e cells may play some role in the development of the tracheobronchial epithelium. Little is known about the development of the nasal respira tory epithelium (RE). Methods: Nasal respiratory mucosa from fetal and newborn humans was examined to determine immunoreactivity for PGP and calbindin. Results: At all stages studied, cells of different morphol ogies displayed PGP-like immunoreactivity (-LI) and calbindin-LI. Colu mnar immunoreactive cells for both markers predominated, but labeled c ells of different shapes were also observed. Most labeled columnar cel ls were in the RE at its border with olfactory epithelium (OE); a few similarly labeled columnar cells also appeared in this OE. In the lami na propria, PGP-LI was also seen in numerous thin branching fibers. So me of these branches penetrated into the epithelium, where fiber varic osities appeared to contact cells, some of which also exhibited PGP-LI . Conclusion: This study demonstrates that during development the huma n nasal RE contains different cell types, as illustrated by the assort ment of epithelial cells displaying PGP-LI and calbindin-LI among unla beled cells. Because PGP and calbindin immunoreactivities were found w ithin neuroendocrine cells in previous studies, the present results in dicate that the developing human nasal RE also may support a number of neuroendocrine cells. Furthermore, at least some of these cells may f orm synaptic contacts with nerve fibers from outside the epithelium. ( C) 1997 Wiley-Liss, Inc.