Serial sectioning, electron microscopy, and three-dimensional reconstruction of fine nerve fibres and other extended objects.

Two different techniques for three-dimensional reconstructions of nerve fibres or other extended fine tissue structures were developed to study the afferent innervation of the cat's knee-joint capsule. The re-embedding technique starts with series of semithin sections for light microscopic reconstructions. In a second step, selected semithin sections can be re-embedded for ultramicrotomy to examine ultrastructural details. This method offers the possibility to investigate fine structures over a distance of several hundred micrometres without any loss of ultrastructural information. The serial section-ESI technique is based on the electron spectroscopic imaging of semithin sections. Small tissue blocks are cut into series of either semithin or alternate semi- and ultrathin sections which can be directly used for a complete ultrastructural investigation. Finally, true-to-scale three-dimensional reconstructions are performed by graphical techniques or computer-aided methods.