When is surfactant produced in the fetus?
How are the paricardial, pulmonary and abdominal cavities formed?
-two folds (on either side of the septum transversum in the trilaminar embryo) delineate the pericardial cavity. -Two more folds near the coelomic entrance delineate the two pleural cavities. -Below that is the abdominal cavity
What does the septum transversum form?
The central tendon of the diaphragm
In the folded embryo, where are the pleural cavities, and where do lung buds come from?
The pleural cavities are behind and on either side of the pericardial cavities. Lung buds develop from the laryngotracheal groove, which is from the developing GI tract.
How do the lung buds grow into the pleural cavities?
The grow out, investing with splanchnic mesoderm, and divide.
What is the visceral pleura dervied from? What is the parietal pleural derived from?
Visceral: splanchnic mesoderm
Parietal: somatic mesoderm
What the histological periods in lung development?
Pseudoglandular (8-16 wks): gland-like tissue. vessels develop
Canalicular (17-26 wks) : bronchi grow
Terminal sacs (26 wks-birth): terminal saccules develop. surfactant is present
Alveoli: 32 wks - 8 yrs
What can oligohydramnios cause?
pulmonary hypoplasia, growth restriction, Potter sequence, etc...
What is tracheoesophageal fistula?
When the esophagus fails to separate from the trachea.
What are congenital lung cysts?
What structures form the diaphragm?
The spetum transversum, the 2 pleuroperitoneal folds, the mesoesophagus (mesentry that supports the esophagus) and the muscles of the body wall.
What are some pathologies associated with improper diaphragm development?
Mostly failure to fuse:
- contents of the abdomen can be forced into the thoracic cavity and result in hypoplastic lungs
- failure of the four structures to fuse --> foramen of Bochdalek
What lung features are needed for premature foetuses to survive?
- must have at least terminal saccules to exchange gas
-must have surfactant to keep the lungs from collapsing