Somitogenesis: Difference between revisions
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Seel also [[#Other Species|Other species Somitogenesis]] | |||
Seel also [[Other Species|Somitogenesis | |||
==Mesoderm to Somite== | ==Mesoderm to Somite== | ||
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==Other Species== | ==Other Species== | ||
{{Species somite number table}} | {{Species somite number table}} | ||
===Chicken=== | ===Chicken=== | ||
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===Mouse=== | ===Mouse=== | ||
{{Mouse Somitogenesis table}} | {{Mouse Somitogenesis table}} | ||
===Rat=== | |||
{{LandacreAmstutz1929 table3}} | |||
{{LandacreAmstutz1929 collapsetable3}} | |||
==Additional Images== | ==Additional Images== |
Revision as of 11:31, 12 August 2017
Embryology - 14 Jun 2024 Expand to Translate |
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Introduction
The term used to describe the process of segmentation of the paraxial mesoderm within the trilaminar embryo body to form pairs of somites, or balls of mesoderm. In humans, the first somite pair appears at day 20 and adds caudally at 1 somite pair/90 minutes until on average 44 pairs eventually form.
A somite is added either side of the notochord (axial mesoderm) to form a somite pair. The segmentation does not occur in the head region, and begins cranially (head end) and extends caudally (tailward) adding a somite pair at regular time intervals. The process is sequential and therefore used to stage the age of many different species embryos based upon the number visible somite pairs.
A mesenchymal to epithelial transition defines the outer cellular "shell" of the developing somite, with the core cells remain as a mesenchymal organisation. During early somite development a transient fluid-filled space, the somitocoel, can be identified in each somite and is later lost by cell proliferation. Neural crest cells also enter and mix with the somatic cells.
Somites give rise to many different connective tissues including: cartilage, bone, muscle and tendon.
Mesoderm Links: endoderm | mesoderm | ectoderm | Lecture - Mesoderm | Lecture - Musculoskeletal | 2016 Lecture | notochord | somitogenesis | somite | splanchnic mesoderm | skeletal muscle | smooth muscle | heart | Notochord Movie | musculoskeletal | cartilage | bone | sonic hedgehog | Category:Mesoderm | ||||
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Some Recent Findings
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More recent papers |
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This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.
More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Somitogenesis <pubmed limit=5>Somitogenesis</pubmed> |
Presomitic Mesoderm
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Human First Somites
Human embryo first somite pairs (week 4, Carnegie stage 9)
Somite Number
Week 4 to 5 (GA 6 to 7) covers the main period of human somitogenesis.
Week | Days | Carnegie Stage | Somite Number (pairs) |
---|---|---|---|
Week 3 | 19 - 21 | 9 image | 1 - 3 |
Week 4 | 22 - 23 | 10 image | 4 - 12 |
Week 4 | 23 - 26 | 11 image | 13 - 20 |
Week 4 | 26 - 30 | 12 image | 21 - 29 |
Week 5 | 28 - 32 | 13 image | 30 |
Week 5 | 31 - 35 | 14 image | 30+ |
Seel also Other species Somitogenesis
Mesoderm to Somite
Mesoderm means the "middle layer" and it is from this layer that nearly all the bodies connective tissues are derived. In early mesoderm development a number of transient structures will form and then be lost as tissue structure is patterned and organised. Humans are vertebrates, with a "backbone", and the first mesoderm structure we will see form after the notochord will be somites.
- During segmentation the outer cell layer forms an epithelial layer over a still mesenchymal organization of cells at the core.
- The early forming somite has a cavity at its core called a "somitocoel" that later fills with proliferating mesoderm cells.
Somite to Sclerotome and Dermomyotome
Sclerotome | Dermatome |
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Myotome | |
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Somite initially forms 2 main regional components
- ventromedial region - sclerotome forms vertebral body and intervertebral disc
- dorsolateral region - dermomyotome forms dermis and skeletal muscle
Sclerotome
- The left and right sclerotomes from the same segmental level engulf the notochord.
- Each segmental level is then resegmented in a rostrocaudal direction.
Dermomyotome
- The dermomyotome is divided into a dorsal and ventral half.
- Dorsal - dermatome.
- Ventral - myotome, this will also divide into a dorsal and ventral half that contribute the epaxial and hypaxial skeletal muscle groups respectively.
- hypaxial - muscles of the ventrolateral body wall, girdle, limb and tongue.[8]
- Muscle cells of the limb, tongue and lateral shoulder girdle muscles - derived from somite migrating myogenic precursor cells.
- Muscle cells of the ventrolateral body wall muscles (intercostal and abdominal muscles) and the medial shoulder girdle muscles - derived from the myotome.
Part of the shoulder girdle muscles (trapezius and sternocleidomastoideus) - derived from the lateral plate mesoderm.
Molecular
Pax
Mesoderm Development and Pax[9]
- Links: Developmental Signals - Pax
Mesogenin 1
A master regulator of paraxial presomitic mesoderm differentiation.'[3]
Other Species
Animal Species - Average Somite Pair Number | |
---|---|
Species | Somites Number |
Human | 44 |
Mouse | 65 |
Chicken | 55 |
Lizard (anole) | 72-73 |
Xenopus | 42 |
Zebrafish | 32 |
Chicken
Chicken Somitogenesis | ||
---|---|---|
23-26 hr | 1 somite | |
ca. 23-26 hr | 1-3 | |
26-29 hr | 4 | |
29-33 hr | 7 | |
ca. 33 hr | 8-9 | |
33-38 hr | 10 | |
40-45 hr | 13 | |
45-49 hr | 16 | |
48-52 hr | 19 | |
ca. 50-52 hr | 20-21 | |
50-53 hr | 22 | |
ca. 50-54 hr | 23 | |
50-55 hr | 24-27 | |
51-56 hr | 26-28 | |
52-64 hr | 29-32 | |
3 da | 30-36 | |
3.0-3.5 da | 37- 40 extending into tail | |
3.0-3.5 da | 40-43 | |
3.5 da | 43-44 | |
3.5-4.0 da | Somites extend to tip of tail | |
Hamburger Hamilton Stages | Chicken Development |
Chicken Somitogenesis | ||
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23-26 hr | 1 somite | |
ca. 23-26 hr | 1-3 | |
26-29 hr | 4 | |
29-33 hr | 7 | |
ca. 33 hr | 8-9 | |
33-38 hr | 10 | |
40-45 hr | 13 | |
45-49 hr | 16 | |
48-52 hr | 19 | |
ca. 50-52 hr | 20-21 | |
50-53 hr | 22 | |
ca. 50-54 hr | 23 | |
50-55 hr | 24-27 | |
51-56 hr | 26-28 | |
52-64 hr | 29-32 | |
3 da | 30-36 | |
3.0-3.5 da | 37- 40 extending into tail | |
3.0-3.5 da | 40-43 | |
3.5 da | 43-44 | |
3.5-4.0 da | Somites extend to tip of tail | |
Hamburger Hamilton Stages | Chicken Development |
Mouse
Mouse Somitogenesis | |||||
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Number |
Stage |
||||
12 | 8 | 1 - 7 | 14-15 | 9 | |
13 | 8.5 | (8 - 9.25) | 8 - 12 | 15 | 10 |
14 | 9 | (8.5 - 9.75) | 13 - 20 | 16 | 11 |
15 | 9.5 | (9 - 10.25) | 21 - 29 | 17 - 19 | 12 |
16 | 10 | (9.5 - 10.75) | 30 - 34 | 20 - 21 | 13 - 15 |
17 | 10.5 | (10 - 11.25) | 35 - 39 | 24 - 25 | 13 - 15 |
18 | 11 | (10.5 - 11.25) | 40 - 44 | 25 - 26 | 13 - 15 |
19 | 11.5 | (11 - 12.25) | 45 - 47 | 26 - 27 | 16 |
20 | 12 | (11.5 - 13) | 48 - 51 | 28 | 17 |
21 | 13 | (12.5-14) | 52 - 55 | 29 - 30 | 18 - 19 |
22 | 14 | (13.5-15) | 56 - 60 | 31 | 20 - 23 |
23 | 15 | 60 + | 32 | Fetal period |
Mouse Somitogenesis | |||||
---|---|---|---|---|---|
Stages |
Number |
Stage |
|||
12 | 8 | 1 - 7 | 14-15 | 9 | |
13 | 8.5 | (8 - 9.25) | 8 - 12 | 15 | 10 |
14 | 9 | (8.5 - 9.75) | 13 - 20 | 16 | 11 |
15 | 9.5 | (9 - 10.25) | 21 - 29 | 17 - 19 | 12 |
16 | 10 | (9.5 - 10.75) | 30 - 34 | 20 - 21 | 13 - 15 |
17 | 10.5 | (10 - 11.25) | 35 - 39 | 24 - 25 | 13 - 15 |
18 | 11 | (10.5 - 11.25) | 40 - 44 | 25 - 26 | 13 - 15 |
19 | 11.5 | (11 - 12.25) | 45 - 47 | 26 - 27 | 16 |
20 | 12 | (11.5 - 13) | 48 - 51 | 28 | 17 |
21 | 13 | (12.5-14) | 52 - 55 | 29 - 30 | 18 - 19 |
22 | 14 | (13.5-15) | 56 - 60 | 31 | 20 - 23 |
23 | 15 | 60 + | 32 | Fetal period |
Rat
Maximum Variation | |||||||
---|---|---|---|---|---|---|---|
Age Days-Hrs. |
Number of Litters |
Number of Embryos Counted |
Means | All Embryos | One Litter | Standard Deviation |
Coefficient of Variation % |
10-12 | 1 | 4 | 8.7 | 6-11 | 6-11 | 2.8 | 32 |
10-13 | 1 | 6 1 | 0. 2 | 8-13 | 8-13 | 1.9 | 19 |
10-16 | 2 | 12 | 12.4 | 6-26 | 6-26 | 5.8 | 47 |
10-17 | 6 | 48 | 12.9 | 4-26 | 7-26 | 3 .3 | 26 |
10-18 | 4 | 23 | 14.1 | 6-18 | 9-18 | 3.1 | 22 |
10-19 | 1 | 6 | 14 .3 | 12-17 | 12-17 | 1.2 | 8 |
10-22 | 3 | 16 | 13.1 | 6-19 | 6-14 | 3.9 | 30 |
10-23 | 3 | 17 | 15.2 | 8-18 | 8-18 | 2.4 | 16 |
11-00 | 2 | 0 | 14.6 | 10-17 | 10-17 | 1.9 | 13 |
11-02 | 2 | 15 | 20 . 9 | 17-22 | 17-22 | 1. 3 | 6 |
11-04 | 1 | 10 | 25. 3 | 23-26 | 23-26 | 1.2 | 5 |
11-06 | 1 | 2 | 18.0 | 18-18 | 18-18 | .0 | 0 |
11-08 | 1 | 8 | 25 0 | 23-28 | 23-28 | 1.9 | 8 |
11-09 | 1 | 3 | 22 .0 | 20-25 | 20-25 | 2 . 2 | 10 |
11-10 | 2 | 18 | 26.2 | 21-31 | 21-31 | 2.9 | 11 |
11-11 | 3 | 26 | 25.6 | 14-29 | 14-27 | 3.2 | 12 |
11-12 | 1 | 3 | 26. 7 | 25-28 | 25-28 | 1.2 | 4 |
11-14 | 1 | 3 | 21.3 | 21-22 | 21-22 | .6 | 2 |
11-15 | 1 | 8 | 23.1 | 17-28 | 17-28 | 4 . 0 | 17 |
11-16 | 1 | 7 | 26.7 | 24-28 | 24-28 | 1.3 | 5 |
11-17 | 1 | 7 | 26.1 | 25-28 | 25-28 | 1.1 | 4 |
11-18 | 3 | 25 | 25 .4 | 19-28 | 19-28 | 1.9 | 7 |
11-20 | 2 | 16 | 27.2 | 25-29 | 25-29 | 1.2 | 4 |
23 Ages | 44 | 292 | Av 2.2 | Av 13% | |||
Data Reference[10] Links: rat | somitogenesis |
Table III Showing Means And Variation For Each Age | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Reference: Landacre FL. and Amstutz MM. Data on the number of somites compared with age in the white rat. (1929) Ohio J. Science. 29(6): 253-259. |
Additional Images
References
- ↑ 1.0 1.1 <pubmed>24304493</pubmed>| BMC Dev Biol.
- ↑ <pubmed>27380812</pubmed>
- ↑ 3.0 3.1 <pubmed>25371364</pubmed>
- ↑ <pubmed>22761566</pubmed>| PLoS Comput Biol.
- ↑ <pubmed>21368122</pubmed>
- ↑ <pubmed>17024300</pubmed>
- ↑ <pubmed>20615943</pubmed>
- ↑ <pubmed>24138189</pubmed>
- ↑ <pubmed>24496612</pubmed>| Development
- ↑ 10.0 10.1 Landacre FL. and Amstutz MM. Data on the number of somites compared with age in the white rat. (1929) Ohio J. Science. 29(6): 253-259.
Reviews
<pubmed>18482400</pubmed> <pubmed>21038776</pubmed> <pubmed>21038775</pubmed> <pubmed>17988868</pubmed> <pubmed>17643270</pubmed> <pubmed>17600784</pubmed> <pubmed>17024300</pubmed> <pubmed>15964269</pubmed> <pubmed>15309628</pubmed> <pubmed>15338303</pubmed>
Articles
<pubmed>12649586</pubmed>| Cells Tissues Organs
Search PubMed
Search NLM Online Textbooks: "Somitogenesis" : Developmental Biology | The Cell- A molecular Approach | Molecular Biology of the Cell | Endocrinology
Search Pubmed: Somitogenesis | Formation | Sclerotome | Hes7
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Cite this page: Hill, M.A. (2024, June 14) Embryology Somitogenesis. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Somitogenesis
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G