The most simplest and used definition ofis that they represent the "building blocks" of the human body.
But why stem cells are so special, in comparison with all the others, more than 200 types of adult specialized cells from the structure of
The most simplest and used definition ofis that they represent the "building blocks" of the human body.
But why stem cells are so special, in comparison with all the others, more than 200 types of adult specialized cells from the structure of our tissues and organs?
All adult cells have a well established function or functions and therefore are considered specialized cells.
For instance: muscle cells have the primary function of generating movement, by contraction and relaxation; neurons are highly specialized cells responsible for processing and transmission of cellular signals. But none of these 2 type of adult cells can't fulfill other functions q.e. to secrete bile - only liver cells can do this
Stem cells are first of all unspecialized cells, but they have 2 defined and unique features: self-replication and cellular differentiation.
Self replication or self-renewal means the capacity of stem cells to give rise to a new population of cells identical with themselves. Thus it's possible to maintain for long term a pool of stem cells, responsible for providing new adult cells:
- to replace those which are periodically removed according to their life span (cells ageing) or
- those which are destroyed due to different insults (infections, trauma, different diseases or environmental injuries).
Differentiation capability represents the stem cells feature to divide and give rise to "daughter cells", with a higher degree of definition for their cellular functions (more specialized cells).
For instance: blood forming stem cells give rise to different type of blood cells: red blood cells (named also as erythrocytes), white blood cells (named also as leukocytes) and platelets (named also as thrombocytes).
For a better understanding of self replication and differentiation processes and their importance I'm giving you an example:
Human red cells are important component of the blood, responsible for carrying oxygen to the tissues and take up the carbon dioxide (CO2) resulting from their metabolism processes.
The life span of a human red blood cell is 110-120 days and then, they are destro