Xie Qiaolin, Zeng Nan, Huang Yu, Tuchin Valery V, Ma Hui
Tsinghua University, Graduate School at Shenzhen, Institute of Optical Imaging and Sensing, Shenzhen Key Laboratory for Minimal Invasive Medical Technologies, 2279 Lishui Street, Shenzhen 518055, China.
Tsinghua University, Department of Biomedical Engineering, 1 Tsinghua Yuan, Beijing 100084, China.
Biomed Opt Express. 2019 Jun 13;10(7):3269-3280. doi: 10.1364/BOE.10.003269. eCollection 2019 Jul 1.
In this paper, we monitor the in vitro tissue clearing process of mouse dorsal skin immersed into two types of agents using Mueller matrix microscope. By Mueller matrix polar decomposition, we can see that the major difference between polarization changes due to two kinds of agents is the opposite trend of phase retardance with clearing. For the insight of the connection between different agents with the microstructural and optical changes of cleared tissues, we establish various models to mimic the dynamic process of microphysical features of tissues with clearing time. The mechanisms considered include refractive index matching, collagen shrinkage, more orderly fibers and birefringence variation. We compare the experimental results with simulations based on a single mechanism model and a combined model, respectively, which confirms that an individual possible mechanism cannot explain the polarization phenomena due to clearing. Also by simulations of various clearing models involving two possible mechanisms, we can speculate that formamide and saturated sucrose as agents have respective impacts on tissue features and then cause different polarization changes with clearing. Specifically, collagen shrinkage plus birefringence reduction can better explain the tissue cleared by formamide, and refractive index match plus increased birefringence model is likely to be a proper description of tissue cleared by sucrose. Both simulations and experiments also validate the potential of Mueller matrix microscope as a good tool to understand the interaction between clearing agents and tissues.
在本文中，我们使用穆勒矩阵显微镜监测浸入两种试剂中的小鼠背部皮肤的体外组织透明化过程。通过穆勒矩阵偏振分解，我们可以看到，由于两种试剂导致的偏振变化的主要差异在于相位延迟随透明化的相反趋势。为了深入了解不同试剂与透明化组织的微观结构和光学变化之间的联系，我们建立了各种模型来模拟组织微观物理特征随透明化时间的动态过程。考虑的机制包括折射率匹配、胶原蛋白收缩、纤维更有序以及双折射变化。我们分别将实验结果与基于单一机制模型和组合模型的模拟结果进行比较，这证实了单个可能的机制无法解释由于透明化导致的偏振现象。同样，通过对涉及两种可能机制的各种透明化模型的模拟，我们可以推测，甲酰胺和饱和蔗糖作为试剂对组织特征有各自的影响，进而导致透明化过程中不同的偏振变化。具体而言，胶原蛋白收缩加上双折射降低可以更好地解释由甲酰胺透明化的组织，而折射率匹配加上双折射增加模型可能是对由蔗糖透明化的组织的恰当描述。模拟和实验都验证了穆勒矩阵显微镜作为理解透明化试剂与组织之间相互作用的良好工具的潜力。
