Endocrine - Thymus Development: Difference between revisions
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== Some Recent Findings == | ==Some Recent Findings== | ||
[[File:Human embryo thymus and parathyroid 01.jpg|thumb|Human Embryo (week 6 - 8)<ref name="PMID21203493"><pubmed>21203493</pubmed> | [http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1001251 PLoS Genet.]</ref>]] | |||
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* '''Thymus-associated parathyroid hormone has two cellular origins with distinct endocrine and immunological functions'''<ref name="PMID21203493"><pubmed>21203493</pubmed> | [http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1001251 PLoS Genet.]</ref> "In mammals, parathyroid hormone (PTH) is a key regulator of extracellular calcium and inorganic phosphorus homeostasis. Although the parathyroid glands were thought to be the only source of PTH, extra-parathyroid PTH production in the thymus, which shares a common origin with parathyroids during organogenesis, has been proposed to provide an auxiliary source of PTH, resulting in a higher than expected survival rate for aparathyroid Gcm2⁻/⁻ mutants. However, the developmental ontogeny and cellular identity of these "thymic" PTH-expressing cells is unknown. ...Our data show conclusively that the thymus does not serve as an auxiliary source of either serum PTH or parathyroid function. We further show that the normal process of parathyroid organogenesis in both mice and humans leads to the generation of multiple small parathyroid clusters in addition to the main parathyroid glands, that are the likely source of physiologically relevant "thymic PTH."" [[Endocrine - Parathyroid Development]] | |||
* '''Decision checkpoints in the thymus'''<ref><pubmed>20644572</pubmed></ref>"The development of T cells in the thymus involves several differentiation and proliferation events, during which hematopoietic precursors give rise to T cells ready to respond to antigen stimulation and undergo effector differentiation." | * '''Decision checkpoints in the thymus'''<ref><pubmed>20644572</pubmed></ref>"The development of T cells in the thymus involves several differentiation and proliferation events, during which hematopoietic precursors give rise to T cells ready to respond to antigen stimulation and undergo effector differentiation." | ||
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==Thymus Development== | ==Thymus Development== |
Revision as of 18:10, 21 May 2012
Introduction
The thymus has two origins for the lymphoid thymocytes and the thymic epithelial cells. The thymic epithelium begins as two flask-shape endodermal diverticula that form from the third pharyngeal pouch and extend lateralward and backward into the surrounding mesoderm and neural crest-derived mesenchyme in front of the ventral aorta. The immune system T cells are essential for responses against infections and much research concerns the postnatal development of T cells within the thymus.
--Mark Hill 21:01, 21 February 2011 (EST) This current page relates to the endocrine role of the thymus, for more detailed description of this organ development see Thymus Development.
| Lecture - Head Development | original page
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Some Recent Findings
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Thymus Development
- Endoderm - third pharyngeal pouch
- Week 6 - diverticulum elongates, hollow then solid, ventral cell proliferation
- Thymic primordia - surrounded by neural crest mesenchyme, epithelia/mesenchyme interaction
- Thymus - bone-marrow lymphocyte precursors become thymocytes, and subsequently mature into T lymphocytes (T cells)
- Thymus hormones - thymosins stimulate the development and differentiation of T lymphocytes
B2 Pharyngeal Arch Pouches 3 and 4 (stage 13) | D1 Developing Human Thymus (stage 22) |
Thymus Involution
A postnatal process defined as a decrease in the size, weight and activity of the gland with advancing age. In a recent review[3], thymic involution was described as a result of high levels of circulating sex hormones, in particular during puberty, and a lower population of precursor cells from the bone marrow and finally changes in the thymic microenvironment.
References
- ↑ 1.0 1.1 <pubmed>21203493</pubmed> | PLoS Genet.
- ↑ <pubmed>20644572</pubmed>
- ↑ <pubmed>20354268 </pubmed>
Reviews
<pubmed>19582736</pubmed> <pubmed>18304000</pubmed> <pubmed>17876091</pubmed> <pubmed>16448532</pubmed>
Articles
<pubmed>17625108</pubmed>
Search PubMed
Search April 2010
- Endocrine Development - All (14277) Review (4620) Free Full Text (3140)
Search Pubmed: thymus development
Additional Images
Adult Histology
Terms
- Hassall's corpuscle - thymic corpuscle.
- Thymic corpuscle (=Hassall's corpuscle) a mass of concentric epithelioreticular cells found in the thymus. The number present and size tend to increase with thymus age. (see classical description of Hammar, J. A. 1903 Zur Histogenese und Involution der Thymusdriise. Anat. Anz., 27: 1909 Fiinfzig Jahre Thymusforschung. Ergebn. Anat. Entwickl-gesch. 19: 1-274.)
- thymic epitheliocytes - reticular cells located in the thymus cortex that ensheathe the cortical capillaries, creating and maintain the microenvironment necessary for the development of T-lymphocytes in the cortex.
- T lymphocyte (cell) - named after thymus, where they develop, the active cell is responsible for cell-mediated immunity. (More? Electron micrographs of nonactivate and activated lymphocytes)
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Cite this page: Hill, M.A. (2024, May 21) Embryology Endocrine - Thymus Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Endocrine_-_Thymus_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G