Stem cell types and functions explained
Cell biology • Cell division
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Definition and potency of stem cells
A stem cell is an undifferentiated cell that can divide and produce specialised cells. Potency describes the range of cell types a stem cell can become: totipotent cells form every cell type of the organism and extra-embryonic tissues, pluripotent cells form nearly all body cell types, and multipotent cells form several related cell types found in a specific tissue. Limiting factors for potency include developmental stage, local signals and gene expression patterns that restrict differentiation pathways.
Function of embryonic stem cells
Embryonic stem cells drive early development by dividing and differentiating to generate the full range of specialised tissues required to form the body. Rapid mitotic division of embryonic stem cells produces the diverse cell types needed for organ formation; for example, differentiated cells form the heart very early in development as embryonic cells specialise . Embryonic stem cells lose broad potency as differentiation proceeds, so once a cell becomes specialised it cannot generally revert to a different specialised type.
Function of adult animal stem cells and bone marrow
Adult stem cells reside in specific tissues and provide repair and maintenance. Local adult stem cells replace damaged or worn-out cells by dividing and differentiating into the specialised cell types of that tissue. Bone marrow contains adult stem cells that are multipotent and produce many types of blood cells; these stem cells divide to form red blood cells, several classes of white blood cells and platelets, so bone marrow stem cell activity replenishes the cellular components of the circulatory and immune systems . Limiting factors include the niche environment, signalling molecules and the inherent lineage restrictions of multipotent stem cells.
Function of meristem stem cells in plants
Meristem tissue at shoot and root tips contains plant stem cells that remain active throughout the plant’s life. Meristem cells divide and differentiate to produce all specialised plant cell types such as xylem, phloem, epidermal and mesophyll cells. Continuous meristem activity causes primary growth (lengthening) of shoots and roots and enables regeneration and production of new organs; plant hormones and local signals guide meristem cell fates so that growth direction and organ formation respond to environmental cues fileciteturn0file16turn0file11.
Comparison and practical limits
Embryonic stem cells offer the widest differentiation potential and drive initial organism development, while adult stem cells supply targeted, local repair with more limited potency. Plant meristem cells retain widespread differentiation ability throughout life, permitting cuttings and tissue culture propagation. Practical limits include ethical considerations for embryonic sources, availability and the specialised niche required for adult stem cell function, and the requirement for correct signalling to guide safe and effective differentiation.
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