Expansion microscopy of the chick embryo neural tube to overcome molecular crowding at the centrosomes-cilia

We describe an optimized protocol for application of expansion microscopy (ExM) on chick neural tube (NT) which enables different oriented nanoscale resolution imaging of the centrosomes/ cilia. We explain embryo NT transversal sections and open-book preparations, immunohistochemistry for labeling, and sample preparation for 5-fold tissue expansion. Further, we detail sample orien-tation and Fast Airyscan confocal acquisition and show that NT-ExM retains fluo-rescence signals and overcomes biomolecules crowding in structural features that to date were only imaged with electron microscopy on tissues.

Automated summary

We describe an optimized protocol for expansion microscopy (ExM) on chick neural tube (NT) that allows nanoscale resolution imaging of centrosomes/cilia in different orientations. We explain the preparation of transverse sections and open-book preparations of embryo NT, immunohistochemistry for labeling, and sample preparation for 5-fold tissue expansion. Furthermore, we provide details on sample orientation and Fast Airyscan confocal acquisition, and demonstrate that NT-ExM retains fluorescence signals and overcomes biomolecule crowding in structural features that were previously imaged only with electron microscopy.