Multicellular organisms have found a mechanism to replace the aging, dead and damaged cells with the help of well-developed mechanism of Cell replication using special kind of cell called as Stem Cell. These cells contain DNA with the ability to replicate and produce the copy of its own. This process has also helped in vegetative and sexual reproductions.
The human stem cell can replicate any number of times to produce different cell types. There has been a lot of research work going on to find the mechanism by which these cells divide through which scientists can find an answer to many deadly diseases like Leukemia, Spinal cord injuries, Parkinson’s, Alzheimer’s disease and other diseases which affect brain neurons.
What are Stem cells?
Stem cells are a type of undifferentiated cells which are capable of differentiating into specialized cell type. They are found in multicellular organisms. In humans there are basically 2 types of stem cells:
Embryonic Stem cell:
Embryonic stem cells are found in human embryos at an early stage of development of an embryo after fertilization of an egg with sperm. After 3-6 days of fertilization of the egg with sperm, the special mass of cell called Blastocyst is formed. The blastocyst consists of 50-200 stem cells which are pluripotent in nature and give rise to various forms of cell types found in human body.
Adult or Somatic stem cell:
Adult or somatic stem cells are undifferentiated cells found in the adult human body. Unlike embryonic stem cells, Adult stem cells can only differentiate to single cell type. Adult stem cells differentiate to replace dead and damaged cells in the body of adult humans.
Stem Cell Potency:
Cell potency is the ability of the healthy cell to differentiate into other cell types.
Based on the cell’s ability to differentiate, Stem cells are classified as follows:
Totipotent Stem cells:
Totipotent Stem cells are found in the early stage of fertilization of an egg with sperm. A totipotent stem cell has the ability to divide and give rise to any cell type in the body. Totipotent cells give rise to all body cells including extra-embryonic cells and placental cells.
Pluripotent Stem cell:
Pluripotent stem cells are the one which can differentiate and give rise to all the 3 germ layers like endoderm, ectoderm, and mesoderm. Pluripotent cells are found in embryo between Zygote and Fetus stage of development.
Multipotent Stem cells:
Multipotent Stem cells are the one which can differentiate into the specific cell type of the body. Adult stem cell and Cord blood Stem cells (Blood cells found in placenta attached to the Umbilical cord of child at the time of birth). are an example of Multipotent stem cell. Cord blood Stem cells are a special type of Stem cell which can give rise to different kind of blood cells.
Unipotent Stem cells:
Unipotent Stem Cell can self-renew and give rise to a single type of cells. Skin cells and spermatogenetic stem cells are examples of Unipotent stem cells.
What are different types of stem cells found in the adult Human body?
Below is the different type of Stem cells found in the adult human body.
Hematopoietic Stem Cells:
A type of cell which differentiates to give rise to a different type of blood cells. This type of cells can be found in Umbilical Cord blood and Bone marrows which give rise to red blood cells, white blood cells, and platelets.
Mesenchymal Stem cells:
This stem cell differentiates to give rise to a group of loosely connected cells which are present in Cartilage and Bones.
Neural Stem cell:
Neural Stem cells differentiate to produce neurons and glia of nervous system.
Adipose Stem cells:
Adipose cells differentiate to produce tissue consisting of loosely connected cells which act as energy storage unit of the body. These cells mainly store reserve energy in the form of fat.
Intestinal Stem cells:
These types of cells give rise to intestinal epithelial cells which help in proper functioning of guts.
Endothelial Stem cell:
Endothelial Stem cells are Multipotent Stem cells which differentiate to produce endothelial cells.
Mammary Stem cells:
Mammary stem cells are Multipotent stem cells which help in the formation of mammary glands.
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