It's not accurate to say there are only "three types" of cells that can form during differentiation. Differentiation is a complex process where cells specialize into a vast array of cell types, each with unique functions. Here's a breakdown:

1. Germ Layers: During early embryonic development, three primary germ layers form:

* Ectoderm: This outer layer gives rise to skin, nervous system, hair, nails, and some glands.

* Mesoderm: The middle layer forms muscle, bone, blood, connective tissues, and the circulatory system.

* Endoderm: The inner layer develops into the lining of the digestive and respiratory tracts, liver, pancreas, and other internal organs.

2. Cell Lineage: Within each germ layer, cells further differentiate into specific cell types. For example, ectoderm gives rise to neural stem cells, which then differentiate into various brain and spinal cord cells like neurons and glial cells.

3. Specialized Cell Types: The final product of differentiation are specialized cells, each with unique structures and functions:

* Muscle cells: Contract to produce movement.

* Nerve cells (neurons): Transmit electrical signals for communication.

* Blood cells: Transport oxygen and fight infections.

* Epithelial cells: Line surfaces and protect tissues.

* Connective tissue cells: Provide support and structure.

* And many, many more!

Important Note: The number of cell types that can form during differentiation is vast and continuously being discovered. This diversity reflects the complexity and adaptability of living organisms.