Confocal micrograph measurements of mdx and WT mouse NMJs

Confocal micrographs were collected on either a Leica TPS II SP5 or a Zeiss LSM780 microscope using a 40X Oil objective (NA 1.4). Step size was set between 300-500 nm. Laser lines 405 nm, 458 nm, 488 nm, 563 nm, and 633 nm were used as necessary. Images were analyzed in ImageJ (ImageJ, RRID:SCR_003070) by creating maximum projection images from collected stacks. Junctional Area was calculated by thresholding the fluorescent bungartoxin labeled channel and drawing a polygon around the object and measuring the shape’s area. Receptor Area was measured as the thresholded area of the BTX label within the circumscribed region of the AChR. Dispersion Index was calculated as Receptor Area/Junctional Area. The number of AChR fragments (fragmentation) was measured using the objects counter in ImageJ by setting the minimum area for counts as 5 μm². tSC counts were made by counting only fluorescently labeled Schwann cells in proximity to the endplate having coincident nuclear label via DAPI. Axon branch points were measured by creating 3D rotations of the confocal images of fluorescently labeled motor neurons, and then counting the number of times the axon split. Small varicosities of the motor terminal were not counted as branches. <br><br>Included is a compressed oib file of confocal collection. Best opened in ImageJ

本数据集的共聚焦显微图像（confocal micrographs）分别通过徕卡TPS II SP5（Leica TPS II SP5）或蔡司LSM780（Zeiss LSM780）共聚焦显微镜采集，成像时采用40倍油浸物镜（数值孔径NA=1.4）。采集时的图像步长设置为300~500 nm。根据实验需求选用了405 nm、458 nm、488 nm、563 nm及633 nm的激光谱线。

所有图像均在ImageJ（ImageJ, RRID:SCR_003070）中完成分析：首先从采集得到的图像栈中生成最大投影图像。接头面积（Junctional Area）通过以下流程计算：对荧光标记银环蛇毒素的成像通道进行阈值分割，围绕目标区域绘制多边形，随后测量该多边形的面积。受体面积（Receptor Area）则为乙酰胆碱受体（AChR）外接区域内BTX标记的阈值分割面积。分散指数（Dispersion Index）通过受体面积与接头面积的比值计算得到。

AChR片段的数量（即片段化程度）通过ImageJ内置的对象计数工具测定，计数的最小面积阈值设为5 μm²。终末施万细胞（terminal Schwann cells, tSC）计数仅统计运动终板附近、且通过4',6-二脒基-2-苯基吲哚（DAPI）标记显示存在共定位核信号的荧光标记施万细胞。轴突分支点的测定方式为：对荧光标记运动神经元的共聚焦图像进行三维旋转，随后计数轴突的分叉次数；运动神经末梢的微小曲张体不计入分支数量。

本数据集附带一份压缩格式的oib文件，推荐使用ImageJ打开。