Cytokeratin expression and early lens development

Immunohistochemical analysis of cytokeratins and vimentin in human, rabbit and rat lens epithelium during development revealed transient coexpression of both types of intermediate filaments. Cytokeratins were still detectable after the closure of the lens vesicle (rat and rabbit embryos 13 days post conception) and in the epithelial cells located at the anterior side of the lens in 7-week-old human embryos. Different monoclonal antibodies against cytokeratin 8 reacted differently in lens cells but not in other embryonic tissues. In addition, early human and rabbit specimens exhibited cytokeratin immunostaining in the neuroectodermal cells of the eye cup as well as in the surrounding mesenchyme, and in the hyaloid artery. Possible explanations for the loss of cytokeratins during the differentiation of ectodermal and neuroectodermal cells are discussed.