Please enable JavaScript.
Coggle requires JavaScript to display documents.
Embryology: Thoracic Cavity (Diaphragm Development (components ((2)…
Embryology: Thoracic Cavity
Gastrulation
begins at the beginning of week 3
result:
formation of a flat trilaminar germ disc
mesoderm germ layer divides into 3 types
axial mesoderm = notocord
paraxial mesoderm = somites
sclerotome
vertebrae
dermatome
contributes to some of the dermis and some other connective tissue
myotome
epimere
forms the deep layer of dorsal back muscles around the spine
hypomere
forms the muscles of the chest and abdominal body wall (so everything else)
lateral plate mesoderm
somatopleuric mesoderm
forms dermis and the skeletal + connective components of the upper and lower limbs
splanchnopleuric mesoderm
forms the serous membranes that line organs and the body cavities
2D to 3D
intraembryonic coelom
hollow cavity between somatic and splanchnic layers of lateral plate mesoderm
=> this will be further subdivided by the diaphragm into a thoracic cavity and an abdominopelvic cavity
extraembryonic coelom
= future chorionic cavity
the critical conversion of the trilaminar germ disc into a 3D elongated cylinder is accomplished w/ additional growth and folding of the lateral edges of the long oval germ disc
the yolk sac is pinched off by the lateral margins of the folding embryo to form the vitelline stalk (will contribute to the umbilical cord of the fetus)
Diaphragm Development
at the end of week 3 the septum transversum (
somatic mesoderm
) grows from the anterior surface to bridge the intraembryonic coelom
the
septum transversum
originates near the 3-5 cervical segments
the septum transversum then grows and migrates downward to merge with the splanchnic mesoderm of the surrounding gut tube
components
(2) pleuroperitoneal membranes
(3) paraxial mesoderm
(1) septum transversum
(4) splanchnic mesoderm on the body wall
failure(s)
CDH (congenital diaphragmatic hernia)
more common on the left
caused by failure of pleuroperitoneal membranes
presence of abd viscera in the chest causes the heart to be displaced and for the lung to be compressed
Pleuropericardial folds
divide the thoracic cavity into 2 distinct (non touching) pleural cavities and 1 pericardial cavity
Lung Development
steps
(2)
canlicular phase (16-28 weeks): lung tissue becomes vascularized, terminal alveolar sacs created
(3)
saccular phase (28-36 weeks): alveoli get lining, start making surfactant, capillary beds develop
(1)
pseduoglandular period (6-16 weeks): lung looks like a gland, bronchial tree dev. proliferation
(4)
alveolar phase (36 weeks to 8 y/o): membrane between alveolus and capillary beds thins
before: from the primitive gut an outgrowth will develop into the future larynx and trachea (tracheoesophageal tube), from this lube lung buds will form
failures
tracheoesophageal fistulas
failure in the normal separation of the tracheal bud from the esophagus
the epithelial lining of the mucosa of the larynx, trachea, bronchial tree, and simple squamous epithelium of the alveoli come from endoderm