Ber-EP4 immunoreactivity depends on the germ layer origin and maturity of the squamous epithelium

Aim: To map the expression of Ber-EP4 in well-differentiated squamous epith elia. metaplastic squamous epithelia and dysplastic squamous epithelia of d ifferent origins. Methods and results: Squamous epithelium of different origin was stained us ing a standard immunohistochemistry method applied to paraffin sections. We found that normal squamous epithelium of the oral cavity. oesophagus. uter ine cervix. vagina. anal canal, and branchial cysts are Ber-Ep4-negative, a s are the mature squamous metaplasia of bronchial mucosa. urinary bladder m ucosa and uterine cervical mucosa. In contrast. immature squamous metaplasi a of bronchial mucosa, or uterine cervical mucosa, and squamous dysplasia o f oral mucosa of endodermal origin, or uterine cervical mucosa in most case s expressed Ber-EP4. Conclusion: Squamous epithelia of ectodermal origin never express Ber-EP4. whether normal, hyperplastic, dysplastic or neoplastic. In contrast, squamo us epithelium of endodermal origin sometimes contains the target glycoprote ins of Ber-EP4 when immature. metaplastic, dysplastic or neoplastic. The re sults indicate that the differences in expression of Ber-EP4 in squamous ep ithelium depend primarily on germ layer origin, and on the maturity of the epithelium.