Cell Differentiation Definition
Cell differentiation is the process by which young, immature cells develop into specialized cells with individual characteristics and functions. This process involves changes in gene expression that lead to a switch from one pattern of gene expression to another. All cells are believed to derive from stem cells and obtain their specific functions through differentiation.
Cell Differentiation Examples
In Animals
Cell differentiation is the process through which a cell undergoes changes in gene expression to become specialized for a particular function. After fertilization in animals, a single-celled organism called the zygote is formed, which will eventually become an entire organism.
During the early stages of development, the zygote goes through several mitotic divisions, resulting in a group of cells commonly referred to as embryonic stem cells. These stem cells mature and differentiate, turning into specialized cells such as red blood cells, muscle cells, root hair cells, xylem and phloem cells.
Specialization is an essential process in the growth and maturation of embryos. Multicellular organisms can contain hundreds of different types of cells. Humans possess more than 200 different types of specialized cells in their bodies. For example, the gene encoding hemoglobin is active in reticulocytes (precursors of red blood cells), but this gene is inactive in other cell types.
Differentiated cell types include adipose stromal cells, amniotic fluid-derived cell lines, endothelial and epithelial keratinocyte mesothelial smooth muscle. Cell differentiation patterns suppress somatic evolution in long-lived organisms by creating new cell types during development.
In Plants
Plant cell differentiation is the process by which cells become specialized to perform specific functions. One example of plant cell differentiation is the development of tracheary elements (TEs) from parenchyma cells, which are the building blocks of water-conducting tubes in the xylem.
In vitro studies have shown that mesophyll protoplasts from Zinnia elegans can be induced to differentiate into TEs. Another example of plant cell differentiation is the differentiation of branched unicellular trichomes in plants such as Arabidopsis from precursor cells in the protoderm.
Plants contain hundreds of different types of specialized cells, including red blood cells, muscle cells, root hair cells, xylem and phloem cells. During embryonic development, stem cells mature and differentiate into specialized cell types through a process called organogenesis.
Positional signals trigger the formation of precursors for tissue systems, and within each tissue system precursor, cell types must be specified in the proper order. Long-distance signals are also required for proper plant development.
Factors involved in plant cell differentiation include gene expression and environmental cues such as light and temperature. Gene expression plays a crucial role in determining which genes are turned on or off during cell differentiation.
For example, genes encoding enzymes for C3 pathway are expressed only in bundle sheath cells while those encoding Rubisco activase are expressed exclusively in mesophyll cells. Environmental cues can also affect gene expression and influence how a cell differentiates.
Cell Differentiation Process
Cell differentiation is the process by which young, immature cells take on individual characteristics and reach their mature form and function. All cells presumably derive from stem cells and obtain their functional or phenotypical type through cell differentiation.
During the differentiation process, cells gradually become committed towards developing into a given cell type. Here, the state of commitment may be described as “specification” representing a reversible type of commitment or “determination” representing irreversible commitment.
There are two mechanisms that bring about altered commitments in the different regions of the early embryo. These include cytoplasmic localization and induction signaling.
Cytoplasmic localization occurs during the earliest stage of embryo development. The embryo divides without growth and undergoes cleavage divisions that produce blastomeres (separate cells).
Each of these cells inherits a given region of the cytoplasm of the original cell that may contain specific molecules such as RNA or proteins that influence its developmental fate. Induction signaling refers to cascades of signaling events during which a cell or tissue signals to another cell or tissue to influence its developmental fate.
Epigenetic mechanisms are thought to regulate cellular differentiation. Pioneer factors such as Oct4 play an important role in regulating gene expression during cellular differentiation.
Cellular differentiation can also be influenced by factors such as cytokines, growth factors, hormones, extracellular matrix components, and other environmental cues.
