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.
Each individual muscle fiber is innervated by a single branch from a motor neuron. This branch (telodendron) forms a neuromuscular junction (NMJ) with the muscle cell membrane (sarcolemma), Impulses arriving on the nerve fiber are transmitted to the sarcolemma and ultimately cause the contraction of the muscle fiber.