Final answer:
A unipolar cell's dendrites generate a graded potential known as a generator potential, which can initiate an action potential in the axon's initial segment once a certain threshold is reached.
Step-by-step explanation:
The cell in question that transforms an incoming signal into one of graded potential, increasing amplitude, is a unipolar cell that generates a generator potential. This generator potential is produced from the dendrites of a unipolar cell, which in turn generates the action potential in the initial segment of that cell's axon. The graded potential is a change in the membrane potential that varies in size, depending on the size of the stimulus that elicits it. Once the sum of these graded potentials reach a certain threshold, an action potential is initiated, leading to the transmission of an electrical signal along the neuron.
Glial cells, which are various types of neural tissue cells, are largely responsible for the maintenance of the tissue and support of neurons. The process of a generator potential leading to an action potential is crucial for the effective functioning of the nervous system.