Pretest-posttest designs grew from the simpler posttest only designs, and address some of the issues arising with assignment bias and the allocation of participants to groups. One example is education, where researchers want to monitor the effect of a new teaching method upon groups of children.
The neuromuscular junction (NMJ) is the site of communication between motor nerve axons and muscle fibres.It is composed of four specialised cell types: motor neurons, Schwann cells, muscle fibres and the recently discovered kranocytes.he neuromuscular junction (NMJ) is the site of communication between motor nerve axons and muscle fibres.
One motor neuron (nerve cell) may stimulate a few muscle cells or hundreds of them, depending on the. particular muscle and the work it does. One neuron and all the skeletal muscle cells it stimulates are a. motor unit. When a long threadlike extension of the neuron, called the nerve fiber or axon, reaches the. muscle, it branches into a number of axon terminals, each of which forms junctions with the. sarcolemma of a different muscle cell. These junctions are called neuromuscular (literally, ânerve-. muscleâ) junctions.