title: Optical assessment of tissue anisotropy in ex vivo distended rat bladders.
abstract: Microstructural remodelling in epithelial layers of various hollow organs, including changes in tissue anisotropy, are known to occur under mechanical distension and during disease processes. In this paper, we analyze how bladder distension alters wall anisotropy using polarized light imaging (followed by Mueller matrix decomposition). Optical retardance values of different regions of normal rat bladders under different distension pressures are derived. Then optical coherence tomography is used to measure local bladder wall thicknesses, enabling the calculation of the tissue birefringence maps as a measure of the tissue anisotropy. Selected two-photon microscopy is also performed to better understand the compositional origins of the obtained anisotropy results. The dome region of the bladder shows maximum birefringence when the bladder is distended to high pressures, whereas the ventral remains roughly isotropic during distension. In addition, the average anisotropy direction is longitudinal, along the urethra to dome. The derived wall anisotropy trends are based on birefringence as an intrinsic property of the tissue organization independent of its thickness, to aid in understanding the structure-functions relation in healthy bladders. These new insights into the wall microstructure of ex vivo distending bladders may help improve the functionality of the artificially engineered bladder tissues.
authors.affiliation: University of Toronto, Division of Biophysics and Bioimaging, Ontario Cancer Institute/University Health Network and Department of Medical Biophysics, 610 University Avenue, Toronto, Ontario M5G 2M9 Canada. sanaz.alali@utoronto.ca
authors.forename: Sanaz
authors.initials: S
authors.lastname: Alali
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Aitken
authors.forename: Annette
authors.initials: A
authors.lastname: Schröder
authors.forename: Annette
authors.initials: A
authors.lastname: Shröder
authors.forename: Darius J
authors.initials: DJ
authors.lastname: Bagli
authors.forename: I
authors.initials: I
authors.lastname: Alex Vitkin
mesh_terms: D000465:Algorithms; D000818:Animals; D016880:Anisotropy; D001718:Birefringence; D055119:Elastic Modulus / Q000502:physiology; D005260:Female; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008027:Light; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D041623:Tomography, Optical Coherence / Q000379:methods*; D001743:Urinary Bladder / Q000033:anatomy & histology* / Q000502:physiology*