Stem Cells and Ion Channels

Once the zygote has formed by the fusion of the sperm cell with the oocyte, the early embryo quickly races through development, thereby gaining and losing several stages and types of stem cells. Only stem cells until the morula stage (~16–32 cell stage) are called totipotent which means the ability to form a complete, new organism. In contrast, the famous embryonic stem cell derived from the inner cell mass (embryoblast, ICM) exhibits pluripotency, resembling the differentiation capacity to form all cells of the organism, besides the extraembryonic structures when transplanted. These characteristics can also be found in the set-aside germline stem cells. Subsequently, after the formation of the three germ layers during gastrulation, germ layer stem cells are responsible for the generation of cells from the respective germ layer until gaining full functionality in the mature tissue network. The mature organism is full of various adult stem cells, also referred to as tissue-specific stem cells, which are mostly responsible for the cell turnover and regeneration in tissues.