Final answer:
Neurons are the cell type that does not divide to form new cells when fully differentiated.
Step-by-step explanation:
Among the cell types provided, neurons are unique as they do not undergo division once fully differentiated. Neurons, the fundamental units of the nervous system, specialize in transmitting signals. Following their differentiation, neurons lose the capacity for cell division and replication. This post-mitotic nature distinguishes them from other cell types, such as fibroblasts, liver cells, and smooth muscle cells. Unlike these proliferative cell types, neurons exit the cell cycle and typically remain in a non-dividing state throughout their lifespan.
The inability to divide is a critical characteristic of fully differentiated neurons, emphasizing their structural and functional stability. This feature underscores the significance of neuronal development and highlights the challenges associated with repairing or regenerating neural tissue in the event of damage or injury.