Final answer:
The statement that cell differentiation in mammals is generally irreversible is true. Once cells specialize during development, gene expression is permanently altered, establishing distinct cell types with specific functions.
Step-by-step explanation:
Generally, cell differentiation in mammals is irreversible. This is true since, during development, the expression of genes is permanently switched off, leading to a permanent commitment to a specific cell lineage. When a cell differentiates, it undergoes changes in size, shape, metabolic activity, and function. These changes are due to the unique genetic expression of each cell type; they contain the same DNA but only 'read' the portions that are relevant to their function.
The process of differentiation is guided by the action of transcription factors that control which genes will be expressed. As a result, cells specialize into one of hundreds of different cell types in the human body with each assuming unique morphological and physiological characteristics. However, in some cases, adult somatic cells can be induced to become pluripotent stem cells through certain laboratory techniques, which then have the potential to differentiate into multiple cell types, yet under normal conditions, differentiation is irreversible.