Figure 2: Neuron segmentations in the optically cleared spinal cord and dorsal root ganglia. (A) Retrogradely labeled motoneurons in the ventral horn that project their axons in the common peroneal nerve. (B) Higher magnification of labeled and autofluorescent cell bodies (scale bar). (C) Labeled motoneuron cell bodies in higher magnification (scale bar). (D) Raw fluorescence microscopy image of labeled motoneurons. (E) Automated motoneuron segmentations as overlay/merge with the raw data image in D. (F) Automated motoneuron segmentations of the image in D only. (G) The significantly different mean voxel fluorescence intensity per cell of labeled and autofluorescent neurons enables precise, automated discrimination of labeled and unlabeled motoneurons via fluorescence intensity thresholds (ROC curve in H). (I) Optically cleared L4 dorsal root ganglion after retrograde labeling of the common peroneal nerve. A segmentation of the same DRG is shown in J and K and in higher magnification in L. (M) Similar to motoneurons, labeled sensory neurons can be identified based on fluorescence intensity with high precision and accuracy. Such automated segmentation of fluorescently labeled sensory neurons provide population-wide metrics including cell body volume in (N) and maximum cell body diameter in (O) showing two histogram maxima that may indicate labeling of at least two morphologically distinct neuronal subpopulations. Scale bars: 250 μm in A, 50 μm in B, 30 μm in C, 100 μm in D–F. AUC: Area under the curve; Q: quartile; ROC: receiver operating analysis.