Morphological segmentation with tiling light sheet microscopy to quantitatively analyze the three-dimensional...

Area of Science:

• Neuroscience
• Developmental Biology
• Motor Control

Background:

• Spinal motoneurons are essential for vertebrate motor behaviors.
• Remarkable diversity exists among spinal motoneurons, reflecting specific identities.
• Understanding postnatal 3D morphological changes is key to elucidating this diversity, but high-throughput imaging has been lacking.

Purpose of the Study:

• To quantitatively analyze the 3D morphological changes of spinal motoneurons during postnatal development.
• To investigate the differentiation of motoneuron subpopulations based on soma size.
• To characterize dendritic development in specific motoneuron populations.

Main Methods:

• Tiling light sheet microscopy combined with tissue clearing for high-throughput imaging.
• Analysis of soma size in cervical and lumbar spinal cord motoneurons.
• Adenovirus labeling coupled with 3D volumetric reconstruction for dendritic tracing and measurement.

Main Results:

• Motoneurons innervating upper limbs differentiated into two distinct soma size subpopulations by postnatal day 14.
• Differentiation of lower limb motoneurons was observed to be delayed.
• Dendritic analysis revealed an initial increase followed by a decline in dendrite number with rising dendritic order in lumbar motoneurons.

Conclusions:

• This study provides a quantitative analysis of 3D morphological changes during spinal motoneuron development.
• Findings highlight distinct developmental trajectories and morphological diversity among spinal motoneurons.
• The results contribute to a deeper understanding of the cellular basis of motor control and neuronal diversity.