  Changes in the density and organization of fibrous biological tissues often
accompany the progression of serious diseases ranging from fibrosis to
neurodegenerative diseases, heart disease and cancer. However, challenges in
cost, complexity, or precision faced by existing imaging methodologies pose
barriers to elucidating the role of tissue microstructure in disease. Here, we
leverage the intrinsic optical anisotropy of the Morpho butterfly wing and
introduce Morpho-Enhanced Polarized Light Microscopy (MorE-PoL), a stain- and
contact-free imaging platform which enhances and quantifies the birefringent
material properties of fibrous biological tissues. We develop a mathematical
model, based on Jones calculus, which quantifies fibrous tissue density and
organization. As a representative example, we analyze collagen-dense and
collagen-sparse human breast cancer tissue sections and leverage our technique
to assess the microstructural properties of distinct regions of interest. We
compare our results with conventional Hematoxylin and Eosin (H&E) staining
procedures and second harmonic generation (SHG) microscopy for fibrillar
collagen detection. Our findings demonstrate that our MorE-PoL technique
provides a robust, quantitative, and accessible route toward analyzing
biological tissue microstructures, with great potential for application to a
broad range of biological materials.
