Lecture - Mesoderm Development: Difference between revisions
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{{Header}} | |||
==Introduction== | |||
[[File:Chicken-gastrulation2.jpg|thumb|400px|Mesoderm formation]] | |||
Having now reached week 3 in development we will now begin to look separately at the 3 transient germ layers ({{ectoderm}}, {{mesoderm}} and {{endoderm}}) formed by the process of {{gastrulation}}. Beginning with the mesoderm layer, the middle embryonic connective tissue (mesenchyme) layer. Transient in terms of temporary structures that will become something else later in development. | |||
'''Mesoderm''' initially forms a multilayered cellular layer separating ectoderm and endoderm, mesoderm also lies outside the embryo as '''extra-embryonic mesoderm''' (covered in placenta lecture). Embryonic mesoderm will form most of the adult connective tissues and muscle. | |||
Towards the end of week 3 this layer begins to "partition" into different transient components based upon their location within the layer and the signals the cells are receiving. This partitioning process can be either in terms of cell differentiation or structural. This lecture will describe these initial regions and the tissues they will eventually form. Note that later lectures (muscle, skeleton, limb, integumentary and heart) will revisit these tissues later in development. | |||
== Objectives == | == Objectives == | ||
{| | |||
| | |||
* Understanding of events during the third week of development | * Understanding of events during the third week of development | ||
* Understanding the process of early somite development | * Understanding the process of early somite development | ||
Line 6: | Line 19: | ||
* Brief understanding of the future fate of mesoderm components | * Brief understanding of the future fate of mesoderm components | ||
* Brief understanding of early heart formation | * Brief understanding of early heart formation | ||
| width=250px|{{Presomitic mesoderm movie 3}} | |||
These are mesoderm cells migrating from the primitive stria. | |||
|} | |||
==Lecture Resources== | |||
{| class="wikitable mw-collapsible mw-collapsed" | |||
! Movies | |||
|- | |||
| valign="bottom"|{{Week 3 mesoderm movie}} | |||
| valign="bottom"|{{Week 3 notochord 1 movie}} | |||
| valign="bottom"|{{Week 3 notochord 2 movie}} | |||
| valign="bottom"|{{Week 3 movie}} | |||
|- | |||
| valign="bottom"|{{Vertebra movie}} | |||
| valign="bottom"|{{Somite movie}} | |||
| valign="bottom"|{{Somitogenesis movie}} | |||
| valign="bottom"|{{Mesoderm migration movie 1}} | |||
| valign="bottom"|{{Presomitic mesoderm movie 3}} | |||
|} | |} | ||
== | {| class="wikitable mw-collapsible mw-collapsed" | ||
===The | ! References | ||
|- | |||
| {{Embryo logocitation}} | |||
| | |||
* [[Week 4]] | [[Mesoderm]] | [[Somitogenesis]] | |||
* Lecture Archive: [https://embryology.med.unsw.edu.au/embryology/index.php?title=Lecture_-_Mesoderm_Development&oldid=194042 2015] | [[Media:2015ANAT2341 Lecture 5 - Mesoderm Development.pdf|2015 PDF]] | [[Media:Mesoderm_2013.pdf|2013 PDF]] | [http://php.med.unsw.edu.au/embryology/index.php?title=Lecture_-_Mesoderm_Development&oldid=97926 2012] | [http://php.med.unsw.edu.au/embryology/index.php?title=Lecture_-_Mesoderm_Development&oldid=61931 2011] | |||
|- | |||
| {{MPT2015cover_citation}} | |||
| The following chapter links only work with a UNSW connection. | |||
* [http://www.unsw.eblib.com.wwwproxy0.library.unsw.edu.au/patron/Read.aspx?p=2074364&pg=104 Fourth to Eighth Weeks of Human Development] | |||
* [http://www.unsw.eblib.com.wwwproxy0.library.unsw.edu.au/patron/Read.aspx?p=2074364&pg=446 Skeletal System] | |||
* [http://www.unsw.eblib.com.wwwproxy0.library.unsw.edu.au/patron/Read.aspx?p=2074364&pg=470 Muscular System] | |||
|- | |- | ||
| | | {{SBBFP2015cover_citation}} | ||
| | | The following chapter links only work with a UNSW connection. | ||
* [http://www.unsw.eblib.com.wwwproxy0.library.unsw.edu.au/patron/Read.aspx?p=2074524&pg=100 Fourth Week: Forming the Embryo] | |||
* [http://www. | * [http://www.unsw.eblib.com.wwwproxy0.library.unsw.edu.au/patron/Read.aspx?p=2074524&pg=190 Development of the Musculoskeletal System] | ||
* [http://www. | |||
|} | |} | ||
{| class="wikitable mw-collapsible mw-collapsed" | |||
{| | ! Recent Research | ||
|- | |- | ||
| | | Some recent papers that relate to mesoderm development. | ||
<pubmed>27506116</pubmed> | |||
<pubmed>27385009</pubmed> | |||
<pubmed>27437584</pubmed> | |||
|} | |} | ||
Take the [[Mesoderm Quiz]]. | |||
==Notochord (Axial mesoderm)== | ==Notochord (Axial mesoderm)== | ||
<gallery> | <gallery caption="Embryo Stage 7 (dorsal)"> | ||
Stage7-sem2.jpg|Embryonic disc (SEM) | |||
Stage7_800x700px.jpg|Embryonic disc | |||
Stage7_primitive-streak-node.jpg|Primitive node and streak | |||
Stage7_cloacal-oral-membranes.jpg|Oral and cloacal membranes | |||
Stage7 notochord.jpg|Axial process | |||
</gallery> | </gallery> | ||
==Mesoderm== | ==Mesoderm== | ||
[[ | [[File:Stage7_mesoderm.jpg|thumb|Stage 7 mesoderm]] | ||
[[File:Trilaminar_embryo.jpg|thumb|The trilaminar embryo]] | |||
* generated from epiblast cells migrating through the primitive streak | * generated from epiblast cells migrating through the primitive streak | ||
* epiblast cells expressing fibroblast growth factor (FGF2) | * epiblast cells expressing fibroblast growth factor (FGF2) | ||
Line 61: | Line 91: | ||
* divides initially into 3 components | * divides initially into 3 components | ||
<gallery> | <gallery caption="Embryo Stage 7 (dorsal)"> | ||
Stage7_paraxial-mesoderm.jpg|paraxial mesoderm | |||
Stage7_intermediate-mesoderm.jpg|intermediate mesoderm | |||
Stage7_lateral-plate.jpg|lateral plate | |||
</gallery> | </gallery> | ||
* Paraxial mesoderm - somites - musculoskeletal structures | * '''Paraxial mesoderm''' - somites - musculoskeletal structures | ||
* Intermediate mesoderm - kidney | * '''Intermediate mesoderm''' - urogenital (kidney and genital) | ||
* Lateral plate mesoderm - body wall structures | * '''Lateral plate mesoderm''' - body wall, body cavities, cardiovascular and GIT structures | ||
== Mesoderm Development== | == Mesoderm Development== | ||
The four images below beginning at week 3 show cross-sections of the trilaminar embryo and the sequence of mesoderm development. | The four images below beginning at week 3 show cross-sections of the trilaminar embryo and the sequence of mesoderm development. | ||
{| | |||
[[ | | [[File:Mesoderm-cartoon1.jpg|250px]] | ||
| [[File:Mesoderm-cartoon2.jpg|250px]] | |||
[[ | |- | ||
| [[File:Mesoderm-cartoon3.jpg|250px]] | |||
| [[File:Mesoderm-cartoon4.jpg|250px]] | |||
|} | |||
==Mesoderm Overview== | ==Mesoderm Overview== | ||
{| | {| | ||
| [[File:Trilaminar_embryo.jpg]] | | [[File:Trilaminar_embryo.jpg]] | ||
| [[File:Stage11 | | [[File:Stage11 sem100.jpg|400px]] | ||
|- valign="top" | |- valign="top" | ||
|''' Week 3''' | |''' Week 3''' | ||
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Compare this week 3 trilaminar embryo with the week 4 embryo. | Compare this week 3 trilaminar embryo with the week 4 embryo. | ||
* '''Mesenchyme''' - embryonic connective tissue, describes the cell morphology (developmental transitions: epithelial to mesenchymal, mesenchymal to epithelial) | |||
(Note - 2 these images are not to scale) | (Note - 2 these images are not to scale) | ||
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Compare the mesoderm structures to those formed by ectoderm (neural tube and epidermis) and endoderm (epithelia of developing gastrointestinal tract). | Compare the mesoderm structures to those formed by ectoderm (neural tube and epidermis) and endoderm (epithelia of developing gastrointestinal tract). | ||
|} | |||
{| | |||
! Human Embryo Week 4 ([[Carnegie stage 10]]) - transverse section | |||
|- | |||
| [[File:Stage10 K12202-01.jpg|300px]] | |||
| [[File:Stage10 K12202-02.jpg|300px]] | |||
|} | |||
==Paraxial Mesoderm== | |||
[[File:Chick33h.jpg|thumb|150px|Hamburger & Hamilton Stage 10 (33 hours)<br> | |||
[[Media:Chicken_presomitic_mesoderm_03.mp4|Presomitic mesoderm migration (chicken)]]]] | |||
{| | {| | ||
| | | | ||
* lies adjacent to notochord and forms 2 components | * lies adjacent to axial mesoderm (notochord) and forms 2 components: | ||
** Head - unsegmented paraxial mesoderm | ** Head - unsegmented paraxial mesoderm | ||
** Body - segmented paraxial mesoderm | ** Body - segmented paraxial mesoderm | ||
* Generates trunk muscles, skeleton, dermis of skin, blood vessels, connective tissue | |||
Segmented Paraxial Mesoderm | |||
* segments called '''somites''' - transient embryonic structures. | |||
* first pair of somites (day 20) | |||
* thought to be generated by a "clock" (1 pair every 90 minutes) | * segmentation imposes a pattern on nerves, vasculature, vertebra.... | ||
* neural tube begins to close at 4th somite level, 44 pairs of somites | * somites appear in ordered sequence cranial to caudal | ||
| [[ | * appearance so regular used to stage the embryo (Hamburger & Hamilton 1951- chicken) | ||
** thought to be generated by a "clock" (1 pair every 90 minutes) | |||
** neural tube begins to close at 4th somite level, 44 pairs of somites | |||
| [[File:Mesoderm-cartoon2.jpg]] | |||
|} | |} | ||
[[File:Model for Sprouty4 and FGF in mesoderm segmentation.jpg|300px]] | |||
Model for Sprouty4 and FGF in mouse mesoderm segmentation | |||
==Somite Formation== | ==Somite Formation== | ||
[[ | [[File:Stage 9 SEM1.jpg|thumb|200px|Carnegie stage 9 scanning electron microscope image showing somite formation]] | ||
[[File:Stage_13_image_096.jpg|thumb|Carnegie stage 13 somitocoel]] | [[File:Stage_13_image_096.jpg|thumb|200px|Carnegie stage 13 somitocoel]] | ||
[[File:Stage 13 image 066.jpg|thumb|Carnegie stage 13 sclerotome]] | [[File:Stage 13 image 066.jpg|thumb|200px|Carnegie stage 13 sclerotome]] | ||
{| | {| | ||
| [[File: | | {{Presomitic mesoderm movie 3}} | ||
| {{Somitogenesis movie}} | |||
| [[File:Stage10_bf6.jpg|300px]] | |||
|} | |||
{| | |||
| [[Image:Somite cartoon1.png|250px]] | |||
| [[Image:Somite cartoon2.png|250px]] | |||
|- | |- | ||
| | | [[Image:Somite cartoon3.png|250px]] | ||
| [[Image:Somite cartoon4.png|250px]] | |||
[[Image:Somite | |- | ||
| [[Image:Somite cartoon5.png|250px]] | |||
| [[File:Stage11 sem100.jpg|250px]] | |||
|- | |||
| [[File:Stage11 sem13.jpg|250px]] | |||
[[Week 4]] [[Carnegie stage 11]] | |||
| valign=top| | |||
* ball forms through epithelialization and interactions (cell-cell, cell-extracellular matrix, ECM) fibronectin, laminin | * ball forms through epithelialization and interactions (cell-cell, cell-extracellular matrix, ECM) fibronectin, laminin | ||
* has 2 populations of cells - peripheral columnar and central mesenchymal | * has 2 populations of cells - peripheral columnar and central mesenchymal | ||
* early somite has cavity- somitocoel, cavity is lost during growth | * early somite has cavity- somitocoel, cavity is lost during growth | ||
* somite enclosed by ECM connected to nearby tissues | * somite enclosed by ECM connected to nearby tissues | ||
|} | |||
===Somite Specification === | ===Somite Specification === | ||
[[ | [[File:Somite cartoon5.png|thumb|Somite Specification]] | ||
* Different segmental level somites have to generate different segmental body structures? | * Different segmental level somites have to generate different segmental body structures? | ||
* somite has to form different tissues? | * somite has to form different tissues? | ||
Line 165: | Line 218: | ||
===Dermomyotome=== | ===Dermomyotome=== | ||
* later divides into dorsal '''dermatome''' and ventral '''myotome''' | * later divides into dorsal '''dermatome''' and ventral '''myotome''' | ||
** | ** This topic of muscle and skeleton development will be covered in 2 later lectures Musculoskeletal Development and [[Lecture - Limb Development|Limb Development]]) | ||
* lateral myotome edge migrates at level of limbs | * lateral myotome edge migrates at level of limbs | ||
Line 197: | Line 250: | ||
** Wolffian duct, kidney | ** Wolffian duct, kidney | ||
** '''MH''' - covered in Kidney Development Lecture/Laboratory | ** '''MH''' - covered in Kidney Development Lecture/Laboratory | ||
| [[ | | [[File:Mesoderm-cartoon2.jpg]] | ||
|} | |} | ||
==Lateral Plate Development== | ==Lateral Plate Development== | ||
[[File:Stage7_lateral-plate.jpg|thumb|lateral plate]] | |||
* lying at the surrounding edge of he embryonic disc | * lying at the surrounding edge of he embryonic disc | ||
* a cavity begins in this week to form within the mesoderm itself | * a cavity begins in this week to form within the mesoderm itself | ||
[[ | [[File:Mesoderm-cartoon3.jpg]][[File:Mesoderm-cartoon4.jpg]] | ||
==Intraembryonic Coelom== | ===Intraembryonic Coelom=== | ||
{| | |||
| | |||
* small spaces (vacuoles) begin appearing within the lateral plate mesoderm | * small spaces (vacuoles) begin appearing within the lateral plate mesoderm | ||
* enlarge forming a single cavity within the lateral plate mesoderm | * enlarge forming a single cavity within the lateral plate mesoderm | ||
Line 220: | Line 275: | ||
'''Coelom''' is a general term for a "cavity" and can lie within the embryo (intraembryonic) and outside the embryo (extra embryonic). Later anatomical spaces within the embryo and fetus can also be described as coeloms. | '''Coelom''' is a general term for a "cavity" and can lie within the embryo (intraembryonic) and outside the embryo (extra embryonic). Later anatomical spaces within the embryo and fetus can also be described as coeloms. | ||
| [[File:Mesoderm-cartoon4.jpg]] | |||
|} | |||
===Somatic Mesoderm=== | ===Somatic Mesoderm=== | ||
{| | |||
|The intraembryonic coelom divides the lateral plate into 2 portions | |||
The intraembryonic coelom divides the lateral plate into 2 portions | |||
* closest to ectoderm | * closest to ectoderm | ||
* body wall osteogenic, chrondrogenic and fibrogenic | * body wall osteogenic, chrondrogenic and fibrogenic | ||
* except ribs and scapula | * except ribs and scapula | ||
| [[File:Lateral plate somatic mesoderm cartoon.jpg|300px]] | |||
Lateral plate somatic mesoderm{{#pmid:26589542|PMID26589542}} | |||
|} | |||
===Splanchnic Mesoderm=== | ===Splanchnic Mesoderm=== | ||
* closest to endoderm | {| | ||
* | | | ||
* lies closest to endoderm | |||
* prechordal splanchnic mesoderm - cardiac mesoderm | |||
* splanchnic mesoderm - smooth muscle of gastrointestinal tract (GIT) and blood vessels | |||
[[File:Mesoderm-cartoon4.jpg]] | |||
| [[File:Stage9 bf3.jpg|300px|caption|Stage 9 Dorsal]] | |||
| [[File:Stage9 bf4.jpg|300px|caption|Stage 9 Ventral]] | |||
|} | |||
{{Carnegie stages}} | {{Carnegie stages}} | ||
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:'''Links:''' [[Somitogenesis]] | :'''Links:''' [[Somitogenesis]] | ||
{{ | <references/> | ||
{{2018ANAT2341}} | |||
{{Glossary}} | |||
{{ | {{Footer}} | ||
[[Category:Science-Undergraduate]] | |||
[[Category:Mesoderm]] | [[Category:Mesoderm]] | ||
[[Category:Week 4]] | [[Category:Week 4]] |
Latest revision as of 16:05, 1 October 2019
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Introduction
Having now reached week 3 in development we will now begin to look separately at the 3 transient germ layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. Beginning with the mesoderm layer, the middle embryonic connective tissue (mesenchyme) layer. Transient in terms of temporary structures that will become something else later in development.
Mesoderm initially forms a multilayered cellular layer separating ectoderm and endoderm, mesoderm also lies outside the embryo as extra-embryonic mesoderm (covered in placenta lecture). Embryonic mesoderm will form most of the adult connective tissues and muscle.
Towards the end of week 3 this layer begins to "partition" into different transient components based upon their location within the layer and the signals the cells are receiving. This partitioning process can be either in terms of cell differentiation or structural. This lecture will describe these initial regions and the tissues they will eventually form. Note that later lectures (muscle, skeleton, limb, integumentary and heart) will revisit these tissues later in development.
Objectives
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These are mesoderm cells migrating from the primitive stria. |
Lecture Resources
Movies | |||||||||||||||||||
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References | |
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Hill, M.A. (2020). UNSW Embryology (20th ed.) Retrieved June 10, 2024, from https://embryology.med.unsw.edu.au | |
Moore, K.L., Persaud, T.V.N. & Torchia, M.G. (2015). The developing human: clinically oriented embryology (10th ed.). Philadelphia: Saunders. | The following chapter links only work with a UNSW connection. |
Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R., Francis-West, P.H. & Philippa H. (2015). Larsen's human embryology (5th ed.). New York; Edinburgh: Churchill Livingstone. | The following chapter links only work with a UNSW connection. |
Recent Research |
---|
Some recent papers that relate to mesoderm development.
<pubmed>27506116</pubmed> <pubmed>27385009</pubmed> <pubmed>27437584</pubmed> |
Take the Mesoderm Quiz.
Notochord (Axial mesoderm)
Mesoderm
- generated from epiblast cells migrating through the primitive streak
- epiblast cells expressing fibroblast growth factor (FGF2)
- forms a layer between ectoderm and endoderm with notochord down midline
- present before neural tube formation
- divides initially into 3 components
- Paraxial mesoderm - somites - musculoskeletal structures
- Intermediate mesoderm - urogenital (kidney and genital)
- Lateral plate mesoderm - body wall, body cavities, cardiovascular and GIT structures
Mesoderm Development
The four images below beginning at week 3 show cross-sections of the trilaminar embryo and the sequence of mesoderm development.
Mesoderm Overview
Week 3
Trilaminar embryo Compare this week 3 trilaminar embryo with the week 4 embryo.
(Note - 2 these images are not to scale) |
Week 4
Scanning electron micrograph of a cross-section of a human embryo at week 4 (stage 11). Note the mesoderm structures now present and their relative position and size within the embryo. Compare the mesoderm structures to those formed by ectoderm (neural tube and epidermis) and endoderm (epithelia of developing gastrointestinal tract). |
Human Embryo Week 4 (Carnegie stage 10) - transverse section | |
---|---|
Paraxial Mesoderm
Model for Sprouty4 and FGF in mouse mesoderm segmentation
Somite Formation
|
|
Somite Specification
- Different segmental level somites have to generate different segmental body structures?
- somite has to form different tissues?
- Somite Differentiation
- Compartmentalization accompanied by altered patterns of expression of Pax genes within the somite
- rostro-caudal axis appears regulated by Pax/Hox expression, family of DNA binding transcription factors
Somite initially forms 2 main components
- ventromedial- sclerotome forms vertebral body and intervertebral disc
- dorsolateral - dermomyotome forms dermis and skeletal muscle
Sclerotome
- sclerotome later becomes subdivided
- rostral and caudal halves separated laterally by von Ebner's fissure
- half somites contribute to a single vertebral level body
- other half intervertebral disc
- therefore final vertebral segmentation ‚"shifts"
Dermomyotome
- later divides into dorsal dermatome and ventral myotome
- This topic of muscle and skeleton development will be covered in 2 later lectures Musculoskeletal Development and Limb Development)
- lateral myotome edge migrates at level of limbs
- upper limb first then lower
- mixes with somatic mesoderm
- dermotome continues to contribute cells to myotome
Myotome
- Myotome component of Somite
- epaxial myotome (dorsomedial quarter) forms the dorsal epimere (erector spinae)
- hypaxial myotome (dorsolateral quarter) forms the ventral hypomere, 3 primary muscle layers which are different at neck, thorax and abdomen
Muscle
- Myoblast determining transcription factor MyoD is first expressed in the dorsomedial quadrant of the still epithelial somite whose cells are not yet definitely committed
- basic Helix Loop Helix
- from myotome
Muscle Development Abnormalities
- Duchenne Muscular Dystrophy
- Embryonic muscle development normal and changes occur postnatally
- X-linked dystrophy, large gene encoding cytoskeletal protein - Dystrophin
- progressive wasting of muscle, die late teens
- Becker Muscular Dystrophy, milder form, adult onset
Intermediate Mesoderm
|
Lateral Plate Development
- lying at the surrounding edge of he embryonic disc
- a cavity begins in this week to form within the mesoderm itself
Intraembryonic Coelom
Somatic Mesoderm
The intraembryonic coelom divides the lateral plate into 2 portions
|
Lateral plate somatic mesoderm[1] |
Splanchnic Mesoderm
|
- Carnegie Stages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | About Stages | Timeline
Somitogenesis
(not to scale) |
||||
gastrulation, notochordal process | ||||
primitive pit, notochordal canal | ||||
Somite Number 1 - 3 neural folds, cardiac primordium, head fold | ||||
Somite Number 4 - 12 neural fold fuses | ||||
Somite Number 13 - 20 rostral neuropore closes | ||||
Somite Number 21 - 29 caudal neuropore closes | ||||
Somite Number 30 leg buds, lens placode, pharyngeal arches | ||||
Stage 14
- Links: Somitogenesis
Glossary Links
- Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Cite this page: Hill, M.A. (2024, June 10) Embryology Lecture - Mesoderm Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Lecture_-_Mesoderm_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G