Final answer:
A target neuron can be innervated by a vast number of other neurons, evidenced by the Purkinje cells which may receive up to 200,000 contacts. Innervation is integral for neuronal communication and varies depending on the neuron's location and function.
Step-by-step explanation:
A target neuron can be initially innervated by a variable number of other neurons. This means that its dendrites may receive synaptic inputs from a myriad of other neuronal cells. One example is the Purkinje cell in the cerebellum, which can receive synaptic contacts from up to 200,000 neurons, highlighting the dense and complex network of neuronal communication.
In the context of the autonomic nervous system, a preganglionic neuron originating in the Central Nervous System synapses with a neuron in a ganglion, which then communicates with the target effector organ through neurotransmitters like norepinephrine or acetylcholine, depending on whether it is part of the sympathetic or parasympathetic system, respectively.
Therefore, the number of neurons innervating a target neuron can be immense, underlining the intricate and sophisticated nature of inter-neuronal signaling.