Examples of stem cell in the following topics:
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- Symmetric division maintains stem cell lines and asymmetric division yields differentiated cells.
- Stem cells are undifferentiated biological cells found in multicellular organisms, that can differentiate into specialized cells (asymmetric division) or can divide to produce more stem cells (symmetric division).
- In mammals, there are two broad types of stem cells: embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues.
- Notably, stem cells divide asymmetrically to give rise to two distinct daughter cells: one copy of the original stem cell as well as a second daughter programmed to differentiate into a non-stem cell fate.
- This diagram illustrates stem cell division and differentiation, through the processes of (1) symmetric stem cell division, (2) asymmetric stem cell division, (3) progenitor division, and (4) terminal differentiation.
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- An oligopotent stem cell is limited to becoming one of a few different cell types.
- Stem cells are unique in that they can also continually divide and regenerate new stem cells instead of further specializing.
- There are different stem cells present at different stages of a human's life, including the embryonic stem cells of the embryo, fetal stem cells of the fetus, and adult stem cells in the adult.
- One type of adult stem cell is the epithelial stem cell, which gives rise to the keratinocytes (cells that produce keratin, the primary protein in nails and hair) in the multiple layers of epithelial cells in the epidermis of skin.
- Adult bone marrow has three distinct types of stem cells: hematopoietic stem cells, which give rise to red blood cells, white blood cells, and platelets ; endothelial stem cells, which give rise to the endothelial cell types that line blood and lymph vessels; and mesenchymal stem cells, which give rise to the different types of muscle cells.
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- Three basic categories of cells make up the mammalian body: germ cells, somatic cells, and stem cells.
- Examples of stem and progenitor cells include:
- Hematopoietic stem cells (adult stem cells) from the bone marrow that give rise to red blood cells, white blood cells, and platelets
- Mesenchymal stem cells (adult stem cells) from the bone marrow that give rise to stromal cells, fat cells, and types of bone cells;
- Epithelial stem cells (progenitor cells) that give rise to the various types of skin cells
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- Plant meristems are centers of mitotic cell division, and are composed of a group of undifferentiated self-renewing stem cells from which most plant structures arise.
- In that sense, the meristematic cells are frequently compared to the stem cells in animals, which have an analogous behavior and function.
- Meristematic tissues are cells or group of cells that have the ability to divide.
- Meristematic tissues are found in many locations, including near the tips of roots and stems (apical meristems), in the buds and nodes of stems, in the cambium between the xylem and phloem in dicotyledonous trees and shrubs, under the epidermis of dicotyledonous trees and shrubs (cork cambium), and in the pericycle of roots, producing branch roots.
- Cells of this zone have a stem cell function and are essential for meristem maintenance.
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- Red blood cells, made from bone marrow stem cells, are crucial for the exchange of oxygen and carbon dioxide throughout the body.
- Red blood cells, or erythrocytes (erythro- = "red"; -cyte = "cell"), specialized cells that circulate through the body delivering oxygen to other cells, are formed from stem cells in the bone marrow.
- Hemoglobin is packed into red blood cells at a rate of about 250 million molecules of hemoglobin per cell.
- Only mammals have anucleated red blood cells; however, some mammals (camels, for instance) have nucleated red blood cells.
- The advantage of nucleated red blood cells is that these cells can undergo mitosis.
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- The stem and other plant organs are primarily made from three simple cell types: parenchyma, collenchyma, and sclerenchyma cells.
- The dermal tissue of the stem consists primarily of epidermis: a single layer of cells covering and protecting the underlying tissue.
- When the stem is viewed in cross section, the vascular bundles of dicot stems are arranged in a ring.
- Ground tissue is mostly made up of parenchyma cells, but may also contain collenchyma and sclerenchyma cells that help support the stem.
- The central pith and outer cortex of the (a) flax stem are made up of parenchyma cells.
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- A zygote undergoes rapid cell divisions (cleavage) to form a spherical ball of cells: the blastula; this will further develop into a blastocyst.
- During cleavage, the cells divide without an increase in mass; that is, one large single-celled zygote divides into multiple smaller cells.
- The inner cell mass is also known as the embryoblast; this mass of cells will go on to form the embryo.
- At this stage of development, the inner cell mass consists of embryonic stem cells that will differentiate into the different cell types needed by the organism.
- The typical blastula is a ball of cells.
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- Growth in plants occurs as the stems and roots lengthen.
- It is the result of cell division in the shoot apical meristem .
- It is caused by cell division in the lateral meristem .
- Most primary growth occurs at the apices, or tips, of stems and roots.
- The thickening of the stem that occurs in secondary growth is due to the formation of secondary phloem and secondary xylem by the vascular cambium, plus the action of cork cambium, which forms the tough outermost layer of the stem.
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- Apical meristems contain meristematic tissue located at the tips of stems and roots, which enable a plant to extend in length.
- Intercalary meristems occur only in monocots at the bases of leaf blades and at nodes (the areas where leaves attach to a stem).
- Unlike xylem-conducting cells, phloem-conducting cells are alive at maturity.
- This light micrograph shows a cross section of a squash (Curcurbita maxima) stem.
- The shoot system of a plant consists of leaves, stems, flowers, and fruits.
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- In general, long stretches of the plasma membranes of neighboring plant cells cannot touch one another because they are separated by the cell wall that surrounds each cell.
- How then can a plant transfer water and other soil nutrients from its roots, through its stems, and to its leaves?
- Plasmodesmata are numerous channels that pass between cell walls of adjacent plant cells and connect their cytoplasm; thereby, enabling materials to be transported from cell to cell, and thus throughout the plant .
- Also found only in animal cells are desmosomes, the second type of intercellular junctions in these cell types.
- A plasmodesma is a channel between the cell walls of two adjacent plant cells.