cell differentiation

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Cell differentiation

The mechanism by which cells in a multicellular organism become specialized to perform specific functions in a variety of tissues and organs. Specialized cells are the product of differentiation. The process can be understood only from a historical perspective, and the best place to start is the fertilized egg. Different kinds of cell behavior can be observed during embryogenesis: cells double, change in shape, and attach at and migrate to various sites within the embryo without any obvious signs of differentiation. Cleavage is a rapid series of cell cycles during which the large egg cell is divided into a ball of small cells that line the primitive body cavity as a single layer of embryonic cells. This blastula stage is followed by gastrulation, a complex coordinated cellular migration which not only shapes the embryo but segregates the single-cell layer of the blastula into the three germ layers: endoderm, mesoderm, ectoderm. They give rise to specific cell types; for example, skin and nerves from the ectoderm, the digestive tract from the endoderm, and muscle and connective tissue from the mesoderm. See Blastulation, Cell cycle, Cleavage (embryology), Embryogenesis, Gastrulation

The stable differentiated state is a consequence of multicellularity. A complex organism maintains its characteristic form and identity because populations of specialized cell types remain assembled in a certain pattern. Thus several kinds of cells make up a tissue, and different tissues build organs. The variable assortment of about 200 cell types allows for an almost infinite variety of distinct organisms.

Epithelia, sheets of cells of specific structure and function, cover the outer surface of the vertebrate body and line the lungs, gut, and vascular system. The stable form of a vertebrate is due to its rigid skeleton built from bone and cartilage, forming cells to which the skeletal muscles adhere. All other organs, such as liver and pancreas, are embedded in connective tissue that is derived from fibroblast cells which secrete large amounts of soft matrix material.

Some cells, like nerve cells, are so specialized that they need divide no longer in order to maintain a complex network. Their finite number decreases even during embryonic development. Other cell types are constantly worn out and must be replaced; for example, fibroblasts and pancreas cells simply divide as needed, proving that the differentiated state of cells is heritable, as the daughter cells remember and carry out the same special functions. The renewal of terminally differentiated cells that are unable to divide anymore, such as skin and blood cells, is carried out by stem cells. They are immortal and choose, as they double, whether to remain a stem cell or to embark on a path of terminal differentiation. Most stem cells are unipotent because they give rise to a single differentiated cell type. However, all cell types of the blood are derived from a single blood-forming stem cell, a pluripotent stem cell. A fertilized egg is a totipotent stem cell giving rise to all other cell types that make up an individual organism. See Embryonic differentiation, Embryonic induction, Oogenesis

cell differentiation

[′sel dif·ə‚ren·chē′ā·shən]
(cell and molecular biology)
The series of events involved in the development of a specialized cell having specific structural, functional, and biochemical properties.
References in periodicals archive ?
These studies strongly suggest that ethanol interferes with the ability of differentiating cells to recruit epigenetic modifiers to genes playing key roles in development and to execute the molecular programs governing cellular differentiation.
PPARs and NRFs play essential roles in the integration and regulation of cellular differentiation and metabolism, and TFAM is a key activator of mitochondrial DNA gene transcription.
cell precursor cells expressing Ngn3, methods for using the Ngn3 gene and the Ngn3 polypeptide to alter cellular differentiation in culture or in vivo to produce new .
One possible explanation for the observed enzyme induction of NEP might be based on the relation between cellular differentiation and proliferation.
The results of the characterization of the mutation indicate that the affected protein plays a key role in proper cellular differentiation and morphogenesis.
Then, armed with new knowledge about growth conditions that encouraged cellular differentiation, they were able to compare the ability of strains to do so.
ATRA has been shown to induce cellular differentiation (maturation), a distinctly different role than for retinol, which is involved in the visual cycle.
The company's new proprietary technology, Asymmtate[TM], works with an individual's own skin stem cells to maintain cellular differentiation which decreases as we age.
Objective : Epigenetic processes regulate gene transcription states during cellular differentiation, playing key roles in the maintenance of pluripotency and differentiation.
They will do a systematic study of the effects of cellular micro-environmental factors on cellular differentiation and cartilage formation.
As an important signal transduction molecule, ceramide participates in a variety of cellular transduction pathways and can modulate cell cycle, cellular differentiation, proliferation, and apoptosis.
Meanwhile, those that orchestrate the later stages of cellular differentiation, when cells become increasingly committed to specific functions, are primarily silenced by DNA methylation.