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What Are Stem Cells?
(Released December 2004)

  by Preeti Gokal Kochar  


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Adult stem cells: Somatic stem cells found in adult e.g. bone marrow stem cells

Alginate: A polysaccharide from algae

Autologous transplantation: Transplantation in which donor and recipient are the same

Blastocyst: Early stage in development of animal, stage with a cavity, (blastocele), inner cell mass which gives rise to the embryo and outer cells which form the trophoblast

Blastomere: Early in development, the daughter cells resulting from the cell divisions stick together, each individual cell is a blastomere

Carcinoma: Malignant tumor of epithelial origin

Cell division (asymmetrical): Cell division produces two different types of cells, one like the original mother cell, the other more specialized

Cell division (symmetrical) : Cell division gives rise to two daughter cells both like the original mother cell

Cell fusion: Union of two or more somatic cells to produce a cell with more than one nucleus

Cell migration: Cell acquire motility and move to a different location

Cell-based therapy: Transplanting cells to treat a disease (also called cell therapy)

C-Kit protein: Receptor for Stem cell factor

Cytokines: Hormone-like chemicals synthesized by lymphocytes (and other cells) which have a variety of localized effects such as stimulating cell proliferation

Determination: Process in development in which cell become more specialized and committed to a fate

Differentiation potential: Ability of a stem cell to produce cell types following cell division e.g. a cell with totipotential can produce all cell types of the organism

Dopamine: Neurotransmitter lacking in Parkinson disease patients

Ectoderm: Outermost of the three germ layers gives rise to skin, associated organs and the nervous system of the future organism

Embryoid bodies: Spontaneously formed when embryonic stem cells are plated shows many types of specialized cells e.g. heart muscle cells

Embryonal carcinoma cells: Derived from teratocarcinoma, can be cultured to obtain totipotent stem cells

Embryonal germ cells: Cells destined to become the gonads of the future organism

Embryonal stem cells: Stem cells isolated from the inner cell mass of a blastocyst

Endoderm: The innermost of the three germ layers forms the gut of the future organism

Feeder cells: Layer of cells to provide nutrients to stem cells. Mouse cells are the most commonly used feeder cells

Functional genomics: Study of the role of a particular gene product in the organism

Gastrula: Stage in development when there are three distinct germ layers

Genomics: Study of DNA sequence of an organism

Germ layers: The three layers formed marks the end of early development and beginning of cell migration and determination

Germinal cells: In embryos, cells destined to develop into the germ cells of the gonads in the future organism i.e. egg cells in the female and sperms in the male.

Hematopoiesis: Formation of specialized blood cells from precursor cells

Immune privilege: Certain organs are not easily accessible to immune cells and are refereed to as immune privileged sites e.g. eye

Immunosuppression: Treatment to suppress the immune system used post- transplantation to suppress rejection of the donor graft

Inner cell mass: Group of cells in a blastocyst which develop into the embryo

Karyotype: Number and length of chromosomes in a cell

Lineage stem cells: See progenitor cell

Lymphoid cell: Lymphocytes, cells involved in mounting an immune response

Mesencephalic tissue: Tissue from the mid-brain or mesencephalon

Mesenchymal cells: Stem cells which develop into connective tissue

Mesoderm: Middle layer of the gastrula germ layers

Morula: Early in development, a cluster of dividing cells or blastomeres. Morula is derived from morus meaning raspberry .

Myocardial infarction: Commonly called heart attack. Myocardial infarction results in a disruption of blood supply to the cells in the affected area of the heart

Myocardiocytes: Heart muscle cells (cardiac myocytes)

Myocardium: Muscle tissue of the heart made up of involuntary muscle cells

Neurotrophic factors: Hormones which help growth of neurons, also called nerve growth factors

Oct-4 protein: Transcription factor, octamer-binding protein 4

Oncogenesis: Cancer development

Oncology: Study of cancer

Ontogeny: Study of development of an organism

Plasticity: Stem cell plasticity: Increase in differentiation potential of a cell

Pleuripotential: Ability of a stem cell to differentiate into cell types of the three germ layers, adjective: pleuripotent

Precursor cell: See progenitor cell

Progenitor cell: Stem cell with more specialization and less differentiation potential than a totipotent stem cell

Self-regeneration: For cells, ability to divide and produce more copy of itself

Somatic cell nuclear transfer: Technique in which a nucleus is implanted into an enucleated ovum and the resulting egg is allowed to develop to produce a cloned organism

Stem cell: Undifferentiated cell capable of self-renewal and differentiate into more specialized cells

Stem cell factor: Growth factor which induces cell division and differentiation in blood stem cells

Stromal cells: Mesenchymal cells, give rise to connective tissue

Teratocarcinoma: Germ cell tumor with mixed differentiated tissue and undifferentiated tissue also called teratomas

Terminal cell: Differentiated and specialized cell with limited or no capacity to divide, also called terminally-differentiated cell

Tissue-determined stem cell: See progenitor cell

Tissue engineering: Relatively new field in which synthetic material and biomolecules are used to design a functional part of an organ

Totipotential: Ability of a stem cell to differentiate into all cell types of the organism (totipotent is the adjective)

Transdifferentiation: Direct differentiation of one type of cells to another

Transit-amplifying cell: See Progenitor cell

Trophoblast: Gives rise to placenta and yolksac of the developing embryo

Wilms' tumor: Malignant kidney tumor usually in children (also called neproblastoma)