Stem Cell at Mac App Store analyse

The human body is made up of billions of cells, each one of which is derived from a single fertilised egg cell. However, the bodys cells are not all identical. There are at least two hundred distinct cell types, all with different features and functions, such as neurons (nerve cells), liver cells, skin cells, and so on. These specialised cells are the bodys mature or fully differentiated, cells, all of which are derived from their common ancestors, stem cells. Stem cells are a class of undifferentiated cells that are able to differentiate into specialized cell types. Commonly, stem cells come from two main sources: 1. Embryos formed during the blastocyst phase of embryological development (embryonic stem cells) and 2. 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.). Stem cells have the remarkable potential to develop into many different cell types in the body during early life and growth. In addition, in many tissues they serve as a sort of internal repair system, dividing essentially without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential either to remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell. Stem cells are distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves through cell division, sometimes after long periods of inactivity. Second, under certain physiologic or experimental conditions, they can be induced to become tissue- or organ-specific cells with special functions. In some organs, such as the gut and bone marrow, stem cells regularly divide to repair and replace worn out or damaged tissues. In other organs, however, such as the pancreas and the heart, stem cells only divide under special conditions.