Application of stereology and morphometry on synapses and neurons in the hippocampus of ageing rats : an illustration of problems and solutions

It is generally accepted that synaptic contact zones are dynamic structures able to modify their chemical, physiological and functional properties throughout the lifespan of an organism. Such changes have been shown to be accompanied by alterations in the morphology of synapses. For example, modifications in synaptic ultrastructure have been reported to be involved in learning and memory, in sensitization and in other functions of the CNS (Central Nervous System). However, qualitative changes, if not extreme, are difficult to detect and compare. Therefore, quantification of synaptic ultrastructural features is of prime importance in neurobiology.