Figure 1
Bladder anatomy and basic Brillouin theory to measure bladder mechanics. (A) Schematic representation of the bladder wall: the inner layer of the bladder is the urothelium (U), a cell layer formed by epithelial cells, which sits on the basal membrane; the lamina propria (L) is mainly formed by extracellular matrix (ECM); below the lamina propria there are several concentrical layers of muscle tissue (M), which allow for bladder contraction and urine storage and expulsion. Image taken from BioRender. B) An example of Brillouin spectrum. νB = Brillouin shift; ΓB = Brillouin full width at half maximum; M = complex Longitudinal Modulus, having a real (M’) and imaginary (M’’) part. A Brillouin spectrum consists of a central Rayleigh peak, due to photons scattered at the same frequency of the incident radiation ν0, and two Brillouin peaks, due to photons scattered at lower (Stokes) and higher (Anti-stokes) frequencies than the incident one. The Brillouin peaks are identical, located in the GHz range, centered at ±|νB| and have a full width at half maximum equal to ΓB.
