Gastrulation - Anatomy & Physiology - Revision history

Fiorecastro at 15:23, 5 January 2023

2023-01-05T15:23:14Z

Bara: /* Gastrulation at the Tail Bud */

2016-05-18T10:07:19Z

Gastrulation at the Tail Bud

Ggaitskell at 19:50, 30 June 2014

2014-06-30T19:50:55Z

Bara at 19:03, 28 June 2012

2012-06-28T19:03:52Z

Bara at 18:44, 2 January 2011

2011-01-02T18:44:23Z

Bara at 18:38, 2 January 2011

2011-01-02T18:38:13Z

Aimee.e.hicks at 17:19, 30 December 2010

2010-12-30T17:19:17Z

Aimee.e.hicks: /* Gastrulation at the Tail Bud */

2010-12-30T17:18:24Z

Gastrulation at the Tail Bud

Aimee.e.hicks: /* Gastrulation at the Node */

2010-12-30T17:17:14Z

Gastrulation at the Node

Aimee.e.hicks: /* Gastrulation at the Primitive Streak */

2010-12-30T17:16:19Z

Gastrulation at the Primitive Streak

@@ Line 1: / Line 1: @@
-{{OpenPagesTop}}
 ==Introduction==
@@ Line 71: / Line 71: @@
 }}
-{{OpenPages}}
+==Webinars==
 [[Category:Developmental Biology]][[Category:A&P Done]]

@@ Line 68: / Line 68: @@
 <br>
 {{Template:Learning
-|OVAM = [http://www.uco.es/organiza/departamentos/anatomia-y-anat-patologica/embriologia/T4_Gastrulacion/Gastrulacion_i.html Flash animations showing the process of gastrulation]<br>
+|OVAM = [http://www.uco.es/organiza/departamentos/anatomia-y-anat-patologica/embriologia/MyWeb_i/development.html Flash animations showing the process of gastrulation]<br>
 }}
 {{OpenPages}}
 [[Category:Developmental Biology]][[Category:A&P Done]]

@@ Line 66: / Line 66: @@
 Cells at the posterior of the primitive streak are allocated to form the tail bud. When the primitive streak elongates, these cells don't follow, but migrate posteriorly and form a condensed ball of cells called the tail bud. The tail bud exists to form cells of the hindlimb. Tail notochord and somites form through regression of the tail bud. No endoderm exists in the tail bud. Production of the tail bud is called '''secondary gastrulation''', production of the primitive streak, node and notochord is called '''primary gastrulation'''. Without the tail bud, the notochord would run out of cells before the hindlimb could be made. In animals that have tails, cells at an additional site undergo gastrulation.
 {{OpenPages}}
 [[Category:Developmental Biology]][[Category:A&P Done]]

@@ Line 1: / Line 1: @@
 ==Introduction==
@@ Line 66: / Line 67: @@
 Cells at the posterior of the primitive streak are allocated to form the tail bud. When the primitive streak elongates, these cells don't follow, but migrate posteriorly and form a condensed ball of cells called the tail bud. The tail bud exists to form cells of the hindlimb. Tail notochord and somites form through regression of the tail bud. No endoderm exists in the tail bud. Production of the tail bud is called '''secondary gastrulation''', production of the primitive streak, node and notochord is called '''primary gastrulation'''. Without the tail bud, the notochord would run out of cells before the hindlimb could be made. In animals that have tails, cells at an additional site undergo gastrulation.
 [[Category:Developmental Biology]][[Category:A&P Done]]

@@ Line 36: / Line 36: @@
 ==Mechanism of Gastrulation==
-When the embryo is in its blastula stage it has two cell layers; the epiblast and hypoblast. The '''epiblast''' is columnar, whilst the '''hypoblast''' is cuboidal. Each is a single cell thick. The epiblast is a circular plate of cells that ingress ventrally to give rise to all three cell layers. The hypoblast makes no contribution. The endoderm and mesoderm develop by proliferation and migration of cells of the epiblast, what remains of the epiblast forms the ectoderm.  In gastrulation, cells ingress ventrally from the epiblast to form the three germ layers. Gastrulation occurs at three embryonic sites:
+When the embryo is in its blastula stage it has two cell layers; the epiblast and hypoblast. The '''epiblast''' is columnar, whilst the '''hypoblast''' is cuboidal. Each is a single cell thick. The epiblast is a circular plate of cells that ingress ventrally to give rise to all three cell layers. The hypoblast makes no contribution. The endoderm and mesoderm develop by proliferation and migration of cells of the epiblast, what remains of the epiblast forms the ectoderm.
 .'''Primitive Streak'''
@@ Line 50: / Line 52: @@
 ===Endodermal Ingression===
-Cells of the prospective endoderm are the first to ingress. Ingression involves the breaking of attachments with neighbouring cells of the epiblast and moving ventrally. Cells that have broken free of the epiblast make an epithelial to mesenchymal transition. This is achieved by the breaking of the basal lamina, followed by breaking of the intercellular connections. Cells undergoing this transition change from being regularly shaped to being irregularly shaped. When the cells reach the hypoblast, they interchalate with cells of the hypoblast and revert back to their original epithelial state.
+Cells of the prospective endoderm are the first to ingress. Ingression involves the breaking of attachments with neighbouring cells of the epiblast and moving ventrally. Cells that have broken free of the epiblast make an epithelial to mesenchymal transition. This is achieved by the breaking of the basal lamina, followed by breaking of the intercellular connections. Cells undergoing this transition change from being regularly shaped to being irregularly shaped. When the cells reach the hypoblast, they intercalate with cells of the hypoblast and revert back to their original epithelial state.
 ===Mesodermal Ingression===
-As the streak elongates, it enters the prospective lateral plate mesoderm (LPM) region of the epiblast. Cells of the prospective LPM converge and ingress, making an epithelial to mesenchymal transition. They do not interchalate with the endoderm, but '''remain mesenchymal'''. They then migrate laterally and anteriorly. As the streak extends further, it enters the intermediate and paraxial mesoderm territories, which ingress in a similar fashion. Cells of the LPM are most lateral, then intermediate followed by paraxial mesoderm. As ingression continues and the endoderm continues to interchalate, the hypoblast is pushed laterally. The remaining epiblast forms the ectoderm.
+As the streak elongates, it enters the prospective lateral plate mesoderm (LPM) region of the epiblast. Cells of the prospective LPM converge and ingress, making an epithelial to mesenchymal transition. They do not intercalate with the endoderm, but '''remain mesenchymal'''. They then migrate laterally and anteriorly. As the streak extends further, it enters the intermediate and paraxial mesoderm territories, which ingress in a similar fashion. Cells of the LPM are most lateral, then intermediate followed by paraxial mesoderm. As ingression continues and the endoderm continues to intercalate, the hypoblast is pushed laterally. The remaining epiblast forms the ectoderm.
 ==Gastrulation at the Node==
@@ Line 64: / Line 66: @@
 Cells at the posterior of the primitive streak are allocated to form the tail bud. When the primitive streak elongates, these cells don't follow, but migrate posteriorly and form a condensed ball of cells called the tail bud. The tail bud exists to form cells of the hindlimb. Tail notochord and somites form through regression of the tail bud. No endoderm exists in the tail bud. Production of the tail bud is called '''secondary gastrulation''', production of the primitive streak, node and notochord is called '''primary gastrulation'''. Without the tail bud, the notochord would run out of cells before the hindlimb could be made. In animals that have tails, cells at an additional site undergo gastrulation.
-[[Category:Developmental Biology]][[Category:To Do - AimeeHicks]][[Category:To Do - Review]]
+[[Category:Developmental Biology]][[Category:A&P Done]]

@@ Line 1: / Line 1: @@
 ==Introduction==
-Gastrulation is the process of forming the three germ layers; '''ectoderm''', '''mesoderm''' and '''endoderm'''. It is achieved through a series of highly coordinated series of cell movements. Cells that will form the endodermal and mesodermal organs are brought inside the embryo, whilst cells that will form ectoderm move to spread out over the outside of the embryo.
+Gastrulation is the process of forming the three germ layers; '''ectoderm''', '''mesoderm''' and '''endoderm'''. It is achieved through a series of highly coordinated cell movements. Cells that will form the endodermal and mesodermal organs are brought inside the embryo, whilst cells that will form ectoderm move to spread out over the outside of the embryo.
 '''Ectoderm''' - outside layer
@@ Line 9: / Line 8: @@
 '''Endoderm''' - inner layer
@@ Line 38: / Line 36: @@
 ==Mechanism of Gastrulation==
-When the embryo is in it's blastula stage it has two cell layers; the epiblast and hypoblast. The '''epiblast''' is columnar, whilst the '''hypoblast''' is cuboidal. Each is a single cell thick. The epiblast gives rise to all three cell layers; the hypoblast makes no contribution. The endoderm and mesoderm develop by proliferation and migration of cells of the epiblast, what remains of the epiblast forms the ectoderm. The epiblast is a circular plate of cells. In gastrulation, cells ingress ventrally from the epiblast to form the three germ layers. Gastrulation occurs at three embryonic sites:
+When the embryo is in its blastula stage it has two cell layers; the epiblast and hypoblast. The '''epiblast''' is columnar, whilst the '''hypoblast''' is cuboidal. Each is a single cell thick. The epiblast is a circular plate of cells that ingress ventrally to give rise to all three cell layers. The hypoblast makes no contribution. The endoderm and mesoderm develop by proliferation and migration of cells of the epiblast, what remains of the epiblast forms the ectoderm.  In gastrulation, cells ingress ventrally from the epiblast to form the three germ layers. Gastrulation occurs at three embryonic sites:
 .'''Primitive Streak'''

@@ Line 65: / Line 65: @@
 ==Gastrulation at the Tail Bud==
-*Cells at the posterior of the primitive streak are allocated to form the tail bud. When the primitive streak elongates, these cells don't follow, but migrate posteriorly and form a condensed ball of cells called the tail bud.
+Cells at the posterior of the primitive streak are allocated to form the tail bud. When the primitive streak elongates, these cells don't follow, but migrate posteriorly and form a condensed ball of cells called the tail bud. The tail bud exists to form cells of the hindlimb. Tail notochord and somites form through regression of the tail bud. No endoderm exists in the tail bud. Production of the tail bud is called '''secondary gastrulation''', production of the primitive streak, node and notochord is called '''primary gastrulation'''. Without the tail bud, the notochord would run out of cells before the hindlimb could be made. In animals that have tails, cells at an additional site undergo gastrulation.
-[[Category:Developmental Biology]][[Category:To Do - A&P]]
+[[Category:Developmental Biology]][[Category:To Do - AimeeHicks]]

@@ Line 61: / Line 61: @@
 ==Gastrulation at the Node==
-*The primitive streak stops elongating at about 75% of the way along the length of the posterior - anterior axis.
+The primitive streak stops elongating at about 75% of the way along the length of the posterior - anterior axis. Cells condense at this anterior point of the primitive streak and continue to proliferate; called '''Hensen's Node'''. They then ingress and replace the anterior hypoblast and form foregut endoderm. Cells then migrate anteriorly, leaving the node. These cells will form all of the head mesoderm. The node then regresses posteriorly, destroying the primitive streak and forming the '''notochord''' (axial mesoderm). The notochord begins at the level of the midbrain. Notochord regression also produces paraxial mesoderm. Anterior cells are developing before posterior cells have undergone gastrulation.
 ==Gastrulation at the Tail Bud==

@@ Line 48: / Line 48: @@
 ==Gastrulation at the Primitive Streak==
-*The epiblast is a simple circular plate of cells.
-*Cells proliferate and converge through migration, at one pole of the epiblast. These cells become columnar due to space restrictions.
+The epiblast is a simple circular plate of cells. Cells proliferate and converge through migration, at one pole of the epiblast. These cells become columnar due to space restrictions. This defines the posterior of the embryo. Eventually, convergence causes cells to be displaced anteriorly. As more cells converge, the primitive streak elongates. Cells in the primitive groove change from columnar to wedge shaped, which produces two elevations either side of a groove. Epiblastic cells of the primitive streak begin to ingress ventrally to form the new germ layers. As the primitive streak extends into the anterior, it enters certain "territories" of the epiblast. These are regions, organised from posterior to anterior, which are destined to become certain germ layers.
 ===Endodermal Ingression===
-*Cells of the prospective endoderm are the first to ingress.
-**Ingression involves the breaking of attachments with neighbouring cells of the epiblast and moving ventrally.
+Cells of the prospective endoderm are the first to ingress. Ingression involves the breaking of attachments with neighbouring cells of the epiblast and moving ventrally. Cells that have broken free of the epiblast make an epithelial to mesenchymal transition. This is achieved by the breaking of the basal lamina, followed by breaking of the intercellular connections. Cells undergoing this transition change from being regularly shaped to being irregularly shaped. When the cells reach the hypoblast, they interchalate with cells of the hypoblast and revert back to their original epithelial state.
 ===Mesodermal Ingression===
-The remaining epiblast forms the ectoderm.
+As the streak elongates, it enters the prospective lateral plate mesoderm (LPM) region of the epiblast. Cells of the prospective LPM converge and ingress, making an epithelial to mesenchymal transition. They do not interchalate with the endoderm, but '''remain mesenchymal'''. They then migrate laterally and anteriorly. As the streak extends further, it enters the intermediate and paraxial mesoderm territories, which ingress in a similar fashion. Cells of the LPM are most lateral, then intermediate followed by paraxial mesoderm. As ingression continues and the endoderm continues to interchalate, the hypoblast is pushed laterally. The remaining epiblast forms the ectoderm.
 ==Gastrulation at the Node==