Visual Stem Cell Glossary
- Stem Cells
- Embryonic Stem Cells
- Adult Stem Cells
- The Three Germ Layers
- Directed Differentiation
- Tissue Type
- Mesenchyme Tissue
- Hematopoietic Stem Cells
- Bone Marrow
- Inner Cell Mass
- Model Organism
- Severe Combined Immune-Deficient (SCID) mouse
- Cellular Models
- Cell Types
- Somatic Cells
- Other Terms
- Regenerative Medicine
- Clinical Trials
- Cell Surface Marker Proteins
- Somatic Cell Nuclear Transfer (SCNT)
- Other Stem Cell Glossaries
Stem cells: Cells that are able to (1) self-renew (can create more stem cells indefinitely) and (2) differentiate into (become) specialized, mature cell types.
Adult stem cells (or Somatic Stem Cell): Stem cells that are harvested from tissues in an adult body. These cells are usually multipotent, meaning they can differentiate into cells from some, but not all, of the three germ layers. They are thought to act to repair and regenerate the tissue in which they are found in, but usually they can differentiate into cells of completely different tissue types.
The Three Germ Layers: These are three different tissue types that exist during development in the embryo and that, together, will later make up the body. These layers include the mesoderm, endoderm, and ectoderm.
Endoderm: One of the three germ layers. Specifically, this is the inner layer of cells in the embryo and it will develop into lungs, digestive organs, the liver, the pancreas, and other organs.
Mesoderm: One of the three germ layers. Specifically, this is the middle layer of cells in the embryo and it will develop into muscle, bone, blood, kidneys, connective tissue, and related structures.
Ectoderm: One of the three germ layers. Specifically, this is the outer layer of cells in the embryo and it will develop into skin, the nervous system, sensory organs, tooth enamel, eye lens, and other structures.
Differentiation, Differentiated: The process by which a stem cell turns into a different, mature cell. When a stem cell has become the mature cell type, it is called differentiated and has lost the ability to turn into multiple different cell types; it is also no longer undifferentiated.
Directed differentiation: To tightly control a stem cell to become a specific mature cell type. This can be done by regulating the conditions the cell is exposed to (i.e. specific media supplemented with different factors can be used).
Totipotent: The ability to turn into all the mature cell types of the body as well as embryonic components that are required for development but do not become tissues of the adult body (i.e. the placenta).
Mesenchyme Tissue: Connective tissue from all three germ layers in the embryo. This tissue can become cells that make up connective tissue, cartilage, adipose tissue, the lymphatic system, and bone in the adult body.
Hematopoietic Stem Cells: Stem cells that can create all the blood cells (red blood cells, white blood cells, and platelets). These stem cells reside within bone marrow in adults and different organs in the fetus.
Zygote: The single cell that results from a sperm and egg uniting during fertilization. The zygote undergoes several rounds of cell division before it becomes an embryo (after about four days in humans).
Blastocyst: A very early embryo (containing approximately 150 cells) that has not yet implanted into the uterus. The blastocyst is a fluid-filled sphere that contains a group of cells inside it (called the inner cell mass) and is surrounded by an outer layer of cells (the trophoblast, which forms the placenta).
Inner Cell Mass: A small group of cells that are attached inside the blastocyst. Human embryonic stem cells are created from these cells in blastocysts that are four or five days post-fertilization. The cells from the inner cell mass have the potential to develop into an embryo, then later the fetus, and eventually the entire body of the adult organism.
Embryo: The developing organism from the end of the zygote stage (after about four days in humans) until it becomes a fetus (until 7 to 8 weeks after conception in humans).
Models: A biological system that is easy to study and similar enough to another, more complex system of interest so that knowledge of the model system can be used to better understand the more complex system. Such systems can include cells and whole organisms.
Model organism: An organism that is easy to study and manipulate and is similar enough to another organism of interest so that by understanding the model organism, a greater understanding of the other organism may be gained. For example, rats and mice can be used as model organisms to better understand humans.
Severe Combined Immune-Deficient (SCID) mouse: A mouse lacking a functional immune system, specifically lacking or abnormal T and B lymphocytes. This is due to inbreeding or genetic engineering. They are extensively used for tissue transplants, because they lack an immune system to reject foreign substances, and for studying an immunocompromised system.
Cellular models: A cell system that can be used to understand normal, or diseased, functions that the cell has within the body. By taking cells from the body and studying them outside of the body, in culture, different conditions can be manipulated and the results studied, whereas this can be much more difficult, or impossible, to do within the body.
Regenerative Medicine: A field of research that investigates how to repair or replace damaged tissues, usually by using stem cells. In this manner, stem cells may be differentiated into, or made to become, the type of cell that is damaged and then used in transplants. Also see clinical trials.
Clinical trials: A controlled test of a new drug or treatment on human subjects, normally performed after successful trials with model organisms. ClinicalTrials.gov lists many stem cell clinical trials.
Somatic Cell Nuclear Transfer (SCNT): A technique that uses an egg and a somatic cell (a non-germline cell). The nucleus, which contains the genetic material, is removed from the egg and the nucleus from the somatic cell is removed and combined with the egg. The resultant cell contains the genetic material of the nucleus donor, and is turned into a totipotent state by the egg. This cell has the potential to develop into an organism, a clone of the nucleus donor.
Clone: A genetic, identical copy of an individual organism through asexual methods. A clone can be created through somatic cell nuclear transfer.
- National Institutes of Health (NIH) Stem Cell Glossary
- International Society for Stem Cell Research (ISSCR) Glossary
- EuroStemCell Stem Cell Glossary
Images of “Endoderm,” “Mesoderm,” “Ectoderm,” “Bone Marrow,” “Neurons,” “Cartilage,” “Hand Skeleton,” “Connective and Adipose Tissue,” “Gastrula,” “Clinical Trials,” “Mouse,” “Rat,” “Drosophila,” “C. Elegans,” “Arabidopsis,” “Sea Urchin,” “Xenopus,” “Somatic Cell Nuclear Transfer to Create Dolly” and other images were taken from the Wikimedia Commons and redistributed and altered freely as they are all in the public domain. The image of Hematopoiesis was also taken from the Wikimedia Commons and redistributed according to the GNU Free Documentation License.
© 2009. Teisha Rowland. All rights reserved.