What are Stem Cells?
Stem cells are a type of undifferentiated cells that are capable of differentiating into specialized cell types. Typically, the stem cells come from two main sources:
1. The embryos formed during the blastocyst stage of embryonic development (embryonic stem cells) and
2. Adult tissues (adult stem cells).
Both types are characterized by their power, or the potential to differentiate into different cell types (such as skin, muscle, bone, etc.).
Adult stem cells:
Adult or somatic stem cells exist throughout the body after embryonic development and are found within the different tissue types. These stem cells found in tissues such as brain, bone marrow, blood, blood vessels, skeletal muscles, skin and liver. They remain in a resting state or that do not divide for years until activated by disease or tissue injury. Adult stem cells can divide or self-renew indefinitely, allowing them to generate a wide range of cell types in the organ of origin, or even completely regenerate the original organ. It is generally believed that adult stem cells are limited in their ability to differentiate according to their tissue of origin, but there is some evidence suggesting that can differentiate into other cell types.
Embryonic stem cells:
Embryonic stem cells are derived from a human embryo of four or five days old, ie at the blastocyst stage of development. The embryos are usually extras that have been created in IVF (in vitro fertilization) clinics where several eggs are fertilized in a test tube, but only one is implanted in a reproduction woman.Sexual begins when the sperm one male fertilizes a woman’s ovum (egg) to form a single cell called a zygote. The single cell zygote begins a series of divisions, the formation of 2, 4, 8, 16 cells, etc. After four to six days – before implantation in the uterus – this mass of cells called a blastocyst. The blastocyst consists of an inner cell mass (embryoblast) and an outer cell mass (trophoblast). The outer cell mass becomes part of the placenta, and inner cell mass is the set of cells that differentiate to become all structures of an adult organism. This mass of this is the source of embryonic stem cells -. Totipotent cells (cells with full potential to become any cell in the body) in a normal pregnancy, the blastocyst stage continues until implantation of the embryo in the uterus, at which the embryo is called a fetus. This usually happens at the end of week 10 of gestation after all the important organs of the body have been created.However, to extract embryonic stem cells, the blastocyst stage signals when to isolate stem cells by placing the “inner cell mass” of the blastocyst in a culture dish containing a nutrient-rich broth. Lacking the necessary stimulation to differentiate, begin to divide and replicate while maintaining their ability to become any cell in the human body. Over time, these undifferentiated cells can be stimulated to create specialized cells.
Stem cell cultures:
Stem cells are extracted from adult tissue or division of a zygote in a culture dish. Once extracted, scientists place the cells in a culture that keeps them controlled more specialized or differentiation, but it usually allows them to divide and replicate. The growth process of a large number of embryonic stem cells has been easier than the cultivation of large quantities of adult stem cells, but progress is being made for both types of cells.