Human Development – Lecture 19 – Body cavities
Folding;
Cephalo-caudal folding; in frontal plate → head/tail
Lateral folding; in sagittal plate → side
Folding occurs around the neural tube, notochord and somties
By week 4 folding is complete; gut tube formed.
Heart has started; ventrally located
Brain and liver formation started.
Heart beat induces development of other internal organs.
Lateral folding;
Somatic/pariental mesoderm + ectoderm (lateral & ventral body
wall) → inner of the most outside of the body
Splanchnic/visceral mesoderm + endoderm (gut wall) → outer of
the internal organs
These 2 makes intraembryonic coelom = intraembryonic cavity =
primitive cavity
Folding completes the primitive cavity apart from;
• Vitelline duct (highest part of yolk sac)
• Connecting stalk
Septum transversum
This creates upper and lower level in primitive cavity
It divides the thorax from abdomen.
It is not a solid barrier; openings are 2
pericardioperitoneal cavities (future pleural cavity)
It is mesenchym that give rise to parts of diaphragm
and the ventral mensentry of the foregut
Caudal part of septum transversum is invaded by hepatic
diverticulum which divides within it to form liver and gives
rise to the ventral mesentery of the foregut
Heart – septum transversum – liver
More cavities to come;
• Thoracic cavity
o Superior mediastinum; borstbeen
o Pleural cavity; lungs
o Pericardial cavity; heart
• Diaphragm
• Abdominal cavity → peritoneal cavity
• Pelvic cavity
Folding;
Cephalo-caudal folding; in frontal plate → head/tail
Lateral folding; in sagittal plate → side
Folding occurs around the neural tube, notochord and somties
By week 4 folding is complete; gut tube formed.
Heart has started; ventrally located
Brain and liver formation started.
Heart beat induces development of other internal organs.
Lateral folding;
Somatic/pariental mesoderm + ectoderm (lateral & ventral body
wall) → inner of the most outside of the body
Splanchnic/visceral mesoderm + endoderm (gut wall) → outer of
the internal organs
These 2 makes intraembryonic coelom = intraembryonic cavity =
primitive cavity
Folding completes the primitive cavity apart from;
• Vitelline duct (highest part of yolk sac)
• Connecting stalk
Septum transversum
This creates upper and lower level in primitive cavity
It divides the thorax from abdomen.
It is not a solid barrier; openings are 2
pericardioperitoneal cavities (future pleural cavity)
It is mesenchym that give rise to parts of diaphragm
and the ventral mensentry of the foregut
Caudal part of septum transversum is invaded by hepatic
diverticulum which divides within it to form liver and gives
rise to the ventral mesentery of the foregut
Heart – septum transversum – liver
More cavities to come;
• Thoracic cavity
o Superior mediastinum; borstbeen
o Pleural cavity; lungs
o Pericardial cavity; heart
• Diaphragm
• Abdominal cavity → peritoneal cavity
• Pelvic cavity
