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.
The junction between the axon terminals of a neuron and the receiving cell is called a synapse. (Synapses at muscle fibers are also called neuromuscular junctions or myoneural junctions 1  .). Action potentials travel down the axon of the neuron to its end(s), the axon terminal(s). Transmission between neurons is as much as ten times faster than in chemical synapses. 2  Thus electrical synapses can mediate, for example, the very rapid escape response of crayfish that encounter a threat. 3  Electrical synapses in the CNS permit groups of interneurons to fire together.