NEUROMUSCULAR JUNCTION: MORPHOQUANTITATIVE METHODS OF INVESTIGATION

The neuromuscular junction (NMJ) is the area located between the axon terminal and the muscle fiber. It comprises both pre-and postsynaptic structures where the electrical signal is converted into a chemical signal, leading to neurotransmitter release and subsequent muscle contraction. The NMJ undergoes changes due to stimuli such as physical exercise, aging, and nerve or muscle injury, making its analysis crucial. This chapter aims to provide a comprehensive bibliographic review and highlight the key methodologies for morphoquantitative analysis of the postsynaptic receptors at the NMJ. The evaluation is based on scientific articles and studies sourced from database platforms such as PubMed, Scopus, and Google Scholar. We analyzed various measurement techniques, both semi-automated and manual, focusing on variables such as total perimeter, stained perimeter, total area, stained area, dispersion, number of clusters, diameter, cluster-to-area ratio, fragmentation index, NMJ quantity, and integrated density. Our findings indicate that both methods yield similar results, making them valid for assessing NMJ adaptation. However, the semi-automated methodology demonstrated greater precision, as it standardizes measurements until results are generated. Additionally, this method includes supporting materials with instructions for measurement and image adaptation, as well as tables to help in selecting and understanding the relevant variables of interest.