Differentiation

Differentiation

The process of transformation into a different cell type

What is the end point of the development process?

Completely differentiated cells

Mesenchyme

Loosely organized blast cells, usually mesodermal

Characteristics of differentiated cells

1) Specialized cellular structure and/or function 2) Slow or arrested cell cycle progression 3) impaired ability to transform into other cell types

How does the degree of differentiation change throughout development?

Increases during development

How does the number of differentiated cells change throughout development?

Increases during development

Are tissues with highly differentiated cells able to regenerate?

No, as cells become differentiated their ability to divide diminishes and they lose the ability to proliferate. If they can't proliferate, they can't replace themselves.

Development

Progressive proliferation and differentiation of cells from the zygote to the adult.

Neoplasia

abnormal, new growth

Blastomeres

cells from cleavage stage embryos or blastocysts

Generalized cell types

cells lacking specialized characteristics

Stem cells

cells that differentiate into other cell types. They either divide into more stem cells or they differentiate when they divide

Undifferentiated cell types

cells that have not transformed inot a specialized cell type

Progenitor or precursor cells

cells that must differentiate into other cell types and so cannot propagate their own population

Specialized cell types

cells with distinctive morphological characteristics and/or molecular processes

Anaplasia

dedifferentiation to an embryonic cell type

Growth factors

hormones that control cell cycle progression, cellular differentiation or morphogenesis development

Autonomous specification

intracellular signals (within a cell) controlling cellular differentiation

Hormones

none nutrient chemicals secreted by one cell to induce a response in another cell

Intercellular induction

signals between cells controlling cellular differentiation

Differentiated cell types

specialized cells with limited or no ability to transform into other cell types

Blast cells

stem cells from any embryonic stage

Determination

the final phase, when commitment becomes irreversible

Specification

the first phase in commitment, when the fate is still reversible

As development progresses, how do stem cell populations change?

the populations become restricted to produce some cell types but not others (hence, they are pluripotent)

Totipotency

to have the potential to differentiate into any cell type and produce an entire organism (germ line, gametes, zygotes and early blastomeres)

Pluripotency, multipotency

to have the potential to differentiate into multiple cell types

Dedifferentiation

to reverse the process of differentiation. For a specialized cell to transform into a less specialized cell type

Where does the process of development and differentiation begin?

totipotent zygote and early blastomeres

Metaplasia

transformation of one differentiated cell type to another

Commitment

when the developmental fate of a cell becomes restricted, so that it will differentiate in a specific manner