Touch cell dendrite reconstructions

DHH, July 24, 2008

This adult hermaphrodite animal was used by Martin Chalfie and Nichol Thomson (1979) to document the anatomy of the microtubule bundle inside touch cells such as ALM or AVM. For each animal, the same dendrite was photographed in serial section order along the bodywall to determine how many separate microtubules filled the process, and the relative lengths of individual microtubules vs the length of the whole dendrite. All microtubules were found to have the same orientation, with their distal end lying near the outside edge of the bundle, and their proximal end lying deep inside the bundle – individual tubules are actually much shorter than the adult dendrite. In some animals, two dendrites were photographed in each section, and our digital copies show both dendrites as a montage.

Other features seen here include the specialized “mantle”, an extracellular matrix that helps to link the plasma membrane of the dendrite to a thin wedge of hypodermis and the cuticle. Color annotations on some prints show the count of the total number of microtubules, or the start or stop points of single microtubules.