What is the main difference between a monosynaptic and a polysynaptic reflex?

 The main difference between a monosynaptic and a polysynaptic reflex is the number of synapses in the reflex arc.

In a monosynaptic reflex, there is only one synapse between the sensory neuron and the motor neuron in the reflex arc. The sensory neuron directly synapses with the motor neuron, which then sends a signal to the effector, resulting in a rapid and automatic response.

In contrast, in a polysynaptic reflex, there are multiple synapses between the sensory neuron, interneurons, and motor neurons in the reflex arc. Interneurons are additional neurons that are involved in the reflex arc and act as integrating centers between the sensory and motor neurons.