Improved Immunohistochemistry of Mouse Eye Sections Using Davidson's Fixative and Melanin Bleaching

Immunohistochemistry (IHC) and immunofluorescence (IF) are fundamental molecular biology techniques to assess protein expression. However, the melanin present normally in the eye in the uveal tract (choroid, iris, and ciliary body) and the retinal pigment epithelium (RPE) poses a significant challenge for IHC and IF. This is because melanin interferes with both chromogenic and fluorescent detection methods. Additionally, formalin fixation, which is commonly used for IHC, can result in shrinkage and loss of cellular detail in the eye. This protocol provides an optimized approach using Davidson's fixative with a hydrogen peroxide bleaching step to eliminate melanin interference in the mouse eye, improving the quality and interpretability of IHC analyses of the uveal tract and RPE. It is particularly useful for the analysis of uveal melanoma. Key features • Davidson's fixative minimizes shrinkage of ocular tissues and preserves cell structure better than formalin. • Hydrogen peroxide bleaching step removes all melanin, even in highly pigmented samples. • The protocol is compatible with other tissues that require melanin removal.