Dendrites, neurofibrillary tangles

The MAPs vary in number and relative abundance in different cell types MAP2 is principally found in dendrites, whereas tau is restricted to axons. This selective distribution of MAP2 molecules is the result of subcellular sorting of its messenger RNA (Lewis et al., 1989). Currently, there is interest in the observation that tau is a component of the neurofibrillary tangles of Alzheimer s disease (Goedert et al., 1989). 

In AD neurons, there are three main types of neurofibrillary lesions (NFLs) according to their intracellular localization neurofibrillary tangles (NFTs) inside the cell body and apical dendrites, and neuropil threads (NThs) in distal dendrites and dysrophic neurites, associated with senile plaques. Morphologically, three major subtypes of NFTs can be distinguished, corresponding to different evolutionary stages of these lesions. 

Fig. 1. Note the neurofibrillary tangles within the dendrite (A and B) and soma (C). These tangles can be seen continuous with cytoplasmic areas containing neurotubules. A synapse (S) can be seen on the dendrite in A. 9700 X.

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