Stereological studies of TMB-reacted terminals after axonal transport of WGA-HRP - A possibility of characterizing different bouton populations
Abstract
Anterograde transport of lectin-conjugated horseradish peroxidase followed by incubation with tetramethylbenzidine was employed to label the external afferent fibers and their terminals in several somatosensory and reticular nuclei of the cat. Bouton profiles containing the typical needle-shaped reaction products were analyzed stereologically and matched against randomly chosen unlabelled boutons. In the thalamus the external axon terminals from the lateral cervical nucleus, the dorsal column nuclei and the spinal cord were very similar and in comparison with the unlabelled boutons were very large, with loosely packed large synaptic vesicles and a high mitochondrial content. In the lateral reticular nucleus and the lateral cervical nucleus, where the labelled spinal terminals also formed characteristic populations, the boutons from the lumbar spinal cord were larger than those from the cervical cord. The relative number of labelled terminals was calculated in the different regions and found to be generally larger than had previously been assessed from degeneration experiments.