Slide #DMS 096 [Teased muscle fibers; Gold chloride]. Find and study a neuromuscular junction (motor end plate) in Slide #96, a preparation of teased skeletal muscle fibers stained by the gold chloride method. Study the ultrastructure of the neuromuscular junction as illustrated in your textbook. What features are similar to/different from a typical (neuron-to-neuron) synapse? Define a "motor unit".

Motor Nerve Terminals

1. Motor nerve

2. Neuromuscular junctions

This is a low power view of a whole mount of several skeletal muscle fibers and the nerve fiber (axon) that is innervating them. Each terminal arborization of the axon ends in an expanded synaptic region that contacts the muscle fiber and forms the motor end plate.

At medium power, the small terminal branches of an axon are seen and as are their expansions onto the surface of the muscle fiber forming the motor end plate. Note that while a single axon may innervate more than one muscle cell, only a single motor end plate is formed on each muscle fiber, regardless of its length.

At high power, one may appreciate the expansive and complicated architecture of the motor end plate, the details of which are best seen with the electron microscope.