Immunohistochemical Study on Cytokeratin Expression in Tracheal Epithelium of Human Fetus

Oh, Kwang Soo; Nam, Kwang Il; Park, Sung Sik; Park, Sung Sik

Abstract

Trachea is lined by a pseudostratified epithelium which usually expresses a complex mixture of stratified as well as simple epithelial-type cytokeratins. In the present work, the cytokeratin expressions was studied immunohistochemically in the tracheal epithelium and gland of human fetus at 14, 26 and 32 weeks of gestation. The primary antibodies used were CK7, 8, 10, 14, 18, AE8, 5D3, MNFl16 and AE3. In PAS-hematoxylin stain, the tracheal eithelium was composed of pseudostratified ciliated columnar type and consisted of surface, intermediate and basal layers regardless of gestational ages. The PAS positive cells, however, were decreased in number in proportion to gestational ages. The tracheal gland was not fully differentiated at 14 weeks of gestation, and had well differentiated secretory portions consisting mucous and serous cells at 26 and 32 weeks of gestation. The mucous cells and luminal border of the duct were positive for PAS stain. The tracheal eithelium showed different immunoreactivity between cartilageous and membranous portions. In general, CK7 and 5D3 were expressed in surface cells, AE8 in intermediate cells, and MNFl16 and AE3 in the cells of all layers. At 14 weeks of gestation, the tracheal epithelium immunoreacted for CK7, AE8, 5D3, MNFl16 and AE3. The premordium of tracheal gland was positive for 5D3, MNFl16 and AE3. The tracheal epithelium at 26 and 32 weeks of gestation showed same staining properties to those at 14 weeks of gestation. The duct cells at 26 weeks of gestation were immunoreactive for CK7, 8, 14, 18, AE8, 5D3, MNFl16 and AE3, and those at 32 weeks of gestation were immunoreactive for CK7, 14, 5D3, MNFl16 and AE3. The acinar cells at 26 and 32 weeks of gestation were positively stained for CK7, 8, 18, 5D3, MNFl16 and AE3. These results suggest that CK7 and 5D3 may serve as useful markers for mature cilated cells, AE8 (CKl3) for immature ciliated cells, and CKl4 for duct cells in tracheal epithelium and gland.