Which structure contains acetylcholine (ACh) receptors?

The structure that contains acetylcholine (ACh) receptors is the junctional folds. These folds are specialized invaginations of the muscle cell membrane (sarcolemma) located at the neuromuscular junction, where motor neurons communicate with muscle fibers. The junctional folds increase the surface area available for ACh receptors, facilitating the binding of ACh released from the motor neuron.

When ACh binds to these receptors, it triggers a series of events leading to muscle contraction, beginning with the depolarization of the sarcolemma. The effective design of the junctional folds ensures that the signal for muscle contraction is transmitted efficiently and rapidly, playing a crucial role in neuromuscular signaling.