Chapter 7 - The Gut Tube and the Body Cavities Flashcards
What happens with the ventral layer (endoderm) during the 3rd and 4th week?
The endoderm rolls down to form the gut tube.
What happens during the 3rd and 4th week with the neural tube?
The top layer (ectoderm) of the trilaminar embryonic disk forms the neural plate that rolls up into a tube to form the brain and the spinal cord by the process called neurulation.
Which tube is dorsally?
The neural tube
Which tube is ventrally?
The gut tube
What holds the two tubes together?
The middle layer (mesoderm)
What happens with the lateral plate component of the mesoderm during the 3rd and the 4th week?
The lateral plate component spilts into:
- Visceral (splanchnic) layer
- Parital (somatic) layer
Which tube is the visceral layer intimately connected to?
The gut tube
Lateral body wall folds (one on each isde of the embryo)?
Formed by the parietal layer, together with the overlying ectoderm
Primitive body cavity
- The space between the visceral and the parietal layers of lateral plate mesoderm
- at this early stage it is a continous cavity, since it has not yet been subdivided into the pericardial, pleural, and abdominopelvic regions.
When does the intraembryonic mesoderm differentiate into paraxial mesoderm, intermediate mesoderm, and lateral plate mesoderm?
At the end of the 3rd week
Paraxial mesoderm
- Forms somitomers and somites that play a major role in forming the skull and vertebrae
Intermediat mesoderm
- Contributes to the urogenital system
Lateral plate mesoderm
- Is involved in forming the body caivty
Parietal (Somatic) layer
- Is adjacent to the surface ectoderm and continouos with the extraembryonic parietal mesoderm layer over the amnion.
- Parietal (somatic) layer of the lateral plate mesoderm + overlying ectoderm = somatopleure
Somatopleure =
Parietal (somatic) layer of the lateral plate mesoderm + overlying ectoderm
Visceral (splanchnic) layer
- Is adjacent to endoderm forming the gut tube and continuous with the visceral layer of extraembryonic mesoderm covering the yolk sac.
- The visceral (splanchnic) layer of lateral plate mesoderm + underlying endoderm = splanchnopleure.
Splachnopleure =
The visceral (splanchnic) layer of lateral plate mesoderm + underlying endoderm
When is the lateral body wall folds formed?
During the 4th week
What does the lateral body wall folds consist of?
It consist of the parietak layer of lateral plate mesoderm, ovelrying ectoderm, and cells from adjacent somites that migrate into the mesoderm layer across the lateral somitic frontier.
How does the gut tube form?
The gut tube forms when the endoderm layer fold ventrally and closes