FIGURE SUMMARY
Title

Intravital assessment of myelin molecular order with polarimetric multiphoton microscopy

Authors
Turcotte, R., Rutledge, D.J., Bélanger, E., Dill, D., Macklin, W.B., Côté, D.C.
Source
Full text @ Sci. Rep.

P-CARS zebrafish spinal cord model.

(a) The same spinal cord segment can be identified on different imaging sessions using morphological references. (b) The ventral spinal cord contains two Mauthner axons, one on each lateral side (image width: 80 µm). (c) The Mauthner axon can be easily identified with CARS microscopy (image width: 112.5 µm) based on the visualization of (d) its myelin sheaths (image width: 7 µm). (e) Imaging of the same location as in (c) with an orthogonal polarization orientation showing the modulation in CARS intensity. The arrows indicate the orientation of the linear polarization.

Evaluation of promyelination chemical treatments.

(a) The myelin thickness, (b) the MM, and (c) the focal myelination index (FMI) as a function of chemical treatments (Mann-Whitney test, n = 4). (d) CARS image of a Mauthner axon in a GC1-treated zebrafish. (d) Mapping of the MM from P-CARS reveals a discontinuity on the left side. Blue ROIs indicate where the polarization dependence is plot in (f). The black curve is from the focal myelin discontinuity (e-left, MM = 0.17 ± 0.04) and the red curve from the normal region (e-right, MM = 0.34 ± 0.03).

Developmental myelination of the Mauthner axon in live nacre zebrafish.

(a) CARS images of the Mauthner axon on different days (image width: 8.4 µm). Representative images were selected from longitudinal imaging experiments (repeated imaging over time of same fish). (b) The myelin thickness and (c) the MM are plotted as a function of larval age. A steady increase in MM, but not in myelin thickness, was measured between 3 and 5 dpf. R2 for linear regression and p-value for non-zero slope test are given in each graph.

Electron microscopy confirms that P-CARS informs on the nanostructure.

(a) Electron microscopy images at 3 and 5 dpf show the difference in myelin lamellae organization. (b) The entropy decreases significantly between 3 and 5 dpf (Mann-Whitney test, n = 4).

CARS images of a 5 dpf GC1-treated zebrafish taken at two orthogonal polarization orientations: 0° and 90° (width: 112.5 µm). Arrows point MM discontinuities that have a smaller intensity modulation. Comparing MM and intensity images (width: 8.5 µm) from the yellow arrow, the discontinuities can easily be discerned when looking at the discontinuity in the MM image.

CARS images of a 5 dpf DMSO and T3-treated zebrafish taken at two orthogonal polarization orientations: 0° and 90° (width: 56.25 µm).

Acknowledgments
This image is the copyrighted work of the attributed author or publisher, and ZFIN has permission only to display this image to its users. Additional permissions should be obtained from the applicable author or publisher of the image. Full text @ Sci. Rep.