Abstract
Abstract: :
Purpose:To determine the developmental expression pattern of the epidermal growth factor receptor (EGFR) in anterior epithelial/annular pad cells of the embryonic chicken lens. These studies are designed to test the hypothesis that the EGFR influences multiple aspects of lens growth and differentiation. Methods:Anterior ocular segments from embryos of 7, 14, and 21 days of development (7dE, 14dE and 21dE, respectively) were fixed in buffered paraformaldehyde and embedded in paraffin. De-paraffinized sections were sequentially exposed to commercially available EGFR primary antibodies, biotinylated secondary antibodies, avidin-peroxidase complexes and DAB development prior to photography. Results:With these methods, the EGFR protein was found throughout the anterior epithelium and presumptive annular pad of the 7dE. EGFR staining became restricted to the more peripheral regions of the anterior epithelium in 14dE while annular pad cells continued to show detectable staining. The anterior epithelial cells of 21dE were essentially negative but the post-mitotic annular pad cells continued to exhibit staining localized to their basal surfaces. This pattern of EGFR localization in 21dE was seen throughout the annular pad, equatorial cells and persisted into the first few generations of cells entering into the fiber cell mass. Controls in which the primary antiserum was omitted or replaced with pre-immune serum showed no specific staining. Conclusion:These results show the presence of the EGFR in both mitotic cells and post-mitotic populations committed to fiber cell terminal differentiation of the developing chicken lens. However, as embryonic development proceeds, EGFR expression becomes progressively restricted to the annular pad. This suggests an ongoing role for the EGFR in maintaining the fiber cell phenotype in addition to a potential role in effecting the major changes in gene expression characteristic of the transition from embryonic to post-hatching chicken lens growth.
Keywords: 423 growth factors/growth factor receptors • 434 immunohistochemistry • 580 signal transduction