Myelin is a key component of the peripheral nervous system, whose structure anomaly in the digital skin is implicated in neuropathy. Here we demonstrate an in vivo labeling and imaging technique, capable of visualizing myelin sheaths deep in the mouse digital skin. Through material characterization, we verify that 3‐photon fluorescence (3PF) can be generated from a commonly used dye‐ FluoroMyelin Red for labeling myelin, excited at the 1700‐nm window. Topical injection of FluoroMyelin Red in the mouse digit leads to bright labeling of myelin sheaths. Harnessing the deep‐penetration capability of 3‐photon microscopy excited at the 1700‐nm window, we demonstrate that 3PF imaging of FluoroMyelin Red‐labeled myelin sheaths in the mouse digit in vivo can be achieved to a depth 340 μm below the skin surface, revealing both branching bundle of and individual myelin sheaths.

中文翻译：

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小鼠数字皮肤中髓磷脂的3光子显微镜在1700 nm窗口处激发。

髓磷脂是周围神经系统的关键组成部分，其在数字皮肤中的结构异常与神经病有关。在这里，我们演示了一种体内标记和成像技术，能够可视化鼠标数字皮肤深处的髓鞘。通过材料表征，我们验证了可以在1700 nm窗口处激发的常用染料-FluoroMyelin Red产生3-光子荧光（3PF）来标记髓磷脂。在小鼠手指表面局部注射FluoroMyelin Red会导致髓鞘的明亮标记。利用在1700 nm窗口处激发的3光子显微镜的深层穿透能力，我们证明了在小鼠手指体内的荧光素髓鞘红标记的髓鞘鞘的3PF成像可以实现到皮肤表面以下340μm的深度，