Immunohistochemical and Electron Microscopic Study on the Esohageal Epithelium of the Human Fetus

Yoon, Taek Rim; Park, Sung Sik

Abstract

To clarify the developmental characteristics of fetal esophageal epithelium especially ciliated cell, expressions of epidermal growth factor receptor (EGFR) and cytokeratin (CK) in fetal esophageal mucosa (16-24 weeks of gestation) were studied immunohistochemically, and ultrastructure of the ciliated cells was also observed. The expressions of EGFR and CK were identified in labelled streptoavidine biotin immunohistochemical method. Primary antibodies used were EGFR (Ab-4) which is affinity-purified from hyperimmune rabbit sera (Oncogene Science) and monoclonal mouse anti-human cytokeratin (DAK0-CK, MNFl16). The esophageal lumen was lined with stratified ciliated columnar epithelium between 16 and 24 weeks of gestation. The pattern of expression Of EGFR was different with gestational age and epithelial layer. The ciliated cell exhibited variable staining intensity for EGFR at 16 weeks. Some were stained intensively, and others were stained faintly. Number of ciliated cells stained intensively were gradually increased, and most of them were strongly stained at 24 weeks. The superficial non-ciliated cells, however, showed relatively constant staining property of moderate to intense between 16 and 24 weeks. EGFR immunoreactivity was minimal in the basal and intermediate cells at 16 weeks, but became more intense at 24 weeks. CK immunoreactivity in the ciliated cells between 16 and 24 weeks was similar to that of EGFR immunoreactivity. On the other hand, superficial non-ciliated cells were intense for CK staining at 16 weeks, but were very weak to negative at 24 weeks. CK immunoreactivity was intense in basal and intermediate cells between 16 and 24 weeks, but it was almost negative in the some cells of intermediate layer, especially beneath negatively stained non-ciliated cells, at 24 weeks. In electron microscopy, ciliated cells had well organized cilia and dense granules close to Golgi apparatus between 16 and 24 weeks. The cells apparently active in ciliogenesis were also observed. These cells had short microvilli, many centrioles, and dense granules close to Golgi apparatus. The non-ciliated cells contained numerous clear vesicles adluminally clustered at 16 weeks, while they had many dense vesicles of about same size of clear vesicles at 24 weeks. These results demonstrate the expressions of EGFR and CK in esophageal epithelium of human fetus between 16 and 24 weeks of gestational ages, and suggest that the ciliated cells are still proliferative at 24 weeks.