Temporal and spatial evolution of transparency in tissue clearing

Tissue clearing is done to enable detecting signals from fluorescent labels deep within a specimen, permitting three-dimensional imaging of structures within these specimens. This study explores the temporal and spatial evolution of tissue transparency during the clearing process, focusing on the diffusion mechanisms of optical clearing agents, such as benzyl alcohol benzyl benzoate. Axial and radial configurations were studied, with both approaches yielding comparable results. The radial configuration enables simpler exponential fitting, while the axial configuration provides deeper insights through simulations, a key observation being that tissue edges clear faster than the core. Experimental measurements on five tissue types (chicken breast, beef, pork loin, lamb chop, and pig brain) yielded a diffusion constant of 2.7 ± 0.6×10−6 cm2/s.