Translations:Komórki macierzyste/8/en

1. Totipotent stem cells – they are the most primordial cells – the only type of cells capable to differentiate into all types of embryonic cells and form whole organism. They arise as a result of fertilization forming zygote and then in further developmental process they create the blastomers. Totipotent stem cells are capable to form both embryo and extra-embryonic structures such as placenta connecting the embryo with the mothers organism.
2. Pluripotent stem cells – these cells are descendants of totipotent stem cells and can give rise to cells of the three germ layers: ectoderm, endoderm and mesoderm. The cells are capable to organize and form any tissue (except placenta) in the process of embryogenesis. Along with fetal development and formation of individual tissue structures, the cells lose their pluripotent character in favor of tissue-specific character. The pluripotent cells can be found only during embryonic development and they are unable to go back into totipotent cells.
3. Multipotent stem cells– the cells are characterized with ability to differentiate and form tissue within one of the three germ layers
   • The first germ layer (ectoderm) – nerve, epithelium, skin appendages,
   • The second germ layer (endoderm) – digestive system, respiratory system, endocrine system, urinary tract, sense organs,
   • The third germ layer (mesoderm) – bone, cartilage, skeletal muscle, smooth muscles, heart muscle, tendons, ligaments, adipose tissue. The example of multipotent cells of third germ layer are Mesenchymal Stem Cells. Multipotent cells reside in cellular niches, and their number usually decreases with age and with the body's ability to renew itself.
4. Unipotent stem cells– specialized cells with a preserved ability to divide (unlike mature cells), capable to form one cell types of given definite tissue. The example of unipotent stem cells are satellite cells capable to differentiate into myoblasts and then myocytes forming myofibres of skeletal muscle. Another example are osteoblasts capable to differentiate into osteocytes and form bone tissue. The tissue resident unipotent cells respond to damage signals from local environment by activation and starting the process of tissue regeneration.