Embryonic Stem Cells

A stem cell is the building block of the whole body; they are capable of dividing for long periods of time. When it divides it can make any of the 220 different cells in the human body. Not only that, but they are able to reproduce themselves many times over; making them kind of like an internal repair system in many tissues. Stem cells are unspecialized but they can develop into specialized cells. When they do that, it’s called differentiation.

Stem cells are important for living organisms for many reasons. In the 3- to 5-day-old embryo, called a blastocyst, the inner cells give rise to the entire body of the organism, including all of the many specialized cell types and organs such as the heart, lungs, skin, sperm, eggs and other tissues. In some adult tissues, such as bone marrow, muscle, and brain, discrete populations of adult stem cells generate replacements for cells that are lost through normal wear and tear, injury, or disease.

Commonly, stem cells come from two main sources: Embryos formed during the blastocyst phase of embryological development (embryonic stem cells) and Adult tissue (adult stem cells). Both types are generally characterized by their potency, or potential to differentiate into different cell types (such as skin, muscle, bone, etc.). Adult stem cells can be found in already developed tissues such as the heart and brain. They can be found in infants, children, and adults. Somatic cells will stay in a state of not dividing for years until it is called on by disease or tissue injury. They can divide or self-renew infinitely, which allows them to not only repair an organ but regenerate an entire organ completely. Embryonic stem cells include those found within the embryo, the fetus, or the blood from the amillical cord. Depending on where they are harvested, they can give rise to just about any cell in the human