ANHB2212 Lecture Notes - Lecture 7: Lateral Plate Mesoderm, Simple Squamous Epithelium, Peritoneal Cavity
25 May 2018
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Coelomic Cavity:
Intra-embryomic Coelom:
Coelom is a space which develops within intra-embryonic mesoderm:
- Developed around week 3
Divides lateral plate mesoderm into 2 layers
- Somatopleure – ectoderm association
- Visceropleure – endoderm association
Derivatives of I.E.C, are spaces separating body walls from viscera.
- Pericardial cavity – heart
- lined with pericardium
- Pleural cavity – lungs
- lined with pleura
- Peritoneal cavity – abdominal organs
- lined with peritoneum
Linings are thin sheets of CT coated on one side with simple squamous epithelium
(mesothelium).
- Exudes thin film of serous fluid so one side is non-stick and slippery.
- CT side adheres to adjacent tissues (organs/body wall).
Zygosis
Where peritoneum sticks to itself
- Normal process in development of secondarily-retroperitoneal organs (serous
membrane disappears)
- Pathological process in response to injury or infection (adhesions).
Arrangement of serous cavities:
Organs are surrounded by their cavity (don’t lie inside it).
Organs develop adjacent to the coelom then invaginate into the cavity
- As they grow into the cavity, they become
coated by a layer of serous membrane.
Visceral layer: surrounds organ surface
Parietal layer: lines body cavity
Serous cavity surrounds organ
- Visceral and parietal layers are one
continuous membrane
find more resources at oneclass.com
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- Connective layer between visceral and parietal (mesenteries) full of blood vessels,
nerves etc.
I.E.C begins horseshoe shaped in the embryonic disc.
- arch of horseshoe passes in front of oral membrane and
cranial end of neural tube.
When embryo folds sagittally, septum transversum
and heart come to lie ventral near centre of embryo.
- Divides into 3 bits (pericardium, and
pleuroperitoneal canals (left and right
sides).
By week 4:
Pericardium partitioned from rest of coelom
- Septum transversum developed up near
head, so receives nerve supply from phrenic
nerve from cervical region (C 345).
- Phrenic nerve dragged down through thorax,
come to lie between pericardium and pleuro-
peritoneal canals
- helps separate cavities
- can be seen on surface of pericardium in
prosections.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Coelom is a space which develops within intra-embryonic mesoderm: Derivatives of i. e. c, are spaces separating body walls from viscera. Linings are thin sheets of ct coated on one side with simple squamous epithelium (mesothelium). Exudes thin film of serous fluid so one side is non-stick and slippery. Ct side adheres to adjacent tissues (organs/body wall). Normal process in development of secondarily-retroperitoneal organs (serous membrane disappears) Pathological process in response to injury or infection (adhesions). Organs are surrounded by their cavity (don"t lie inside it). Organs develop adjacent to the coelom then invaginate into the cavity. As they grow into the cavity, they become coated by a layer of serous membrane. Visceral and parietal layers are one continuous membrane. Connective layer between visceral and parietal (mesenteries) full of blood vessels, nerves etc. I. e. c begins horseshoe shaped in the embryonic disc. Arch of horseshoe passes in front of oral membrane and cranial end of neural tube.
