Light as a feather: A novel approach for whole- feather microstructure imaging through tissue clearing and...

Feathers have long held a profound symbolic meaning for humanity across cultures and throughout history. Today, the growing scientific interest in feathers highlights their relevance in diverse fields, including avian biology, evolution and biomimetic applications. The development of new methods that can simplify and improve research on feathers is therefore of great importance. This study introduces a simple and effective pipeline for three-dimensional imaging of the internal and external structure of entire bird feathers. We report the clearing of feathers, rendering them entirely transparent - a process that, to the best of our knowledge, has never been achieved before. Our approach makes it possible to image the feather's 3-D architecture on a standard confocal microscope available in most research labs or imaging core facilities. What is more, we performed label-free imaging by autofluorescence detection. Our technique permits high-resolution visualization of micro-structures with minimal preparation and no destructive processing.