Embryology Flashcards
pleuropericardial membranes
Encloses pericardial cavity as the fibrous pericardium. Separates the pericardio-peritoneal canals from the pericardial cavity. Located superior to developing lungs.
Pleuroperitoneal membranes
separates the pericardio-peritoneal canals from the peritoneal cavity. Located inferior to developing lungs. G
4 parts of the diaphragm
Pleuroperitoneal membrane, dorsal mesentery of esophagus, myoblasts from lateral body wall and septum transversum
What does intraembryonic ceolem originally derive from?
Lateral mesoderm
Somatic mesoderm
Forms the parietal pleura
Splanchnic mesoderm
Forms the visceral pleura
pericardioperitoneal canals
future pleural cavity
Communication between extraembryonic coelem (chorionic cavity) and intraembryonic coelem
This is where the midgut herniates out and grows outside of the intraembryonic coelem. Once the IE coelem is big enough to hold all of the contents, it comes back in during week 10 approximately.
Ventral mesentery
Together with dorsal mesentery divides the peritoneal cavity into right and left halves. The ventral mesentery gradually regresses so that peritoneal cavity is a continuous space.
Dorsal mesentery
suspends the foregut, hindgut and midgut into the peritoneal cavity from the posterior abdominal wall.
Location of pericardioperitoneal canal relative to foregut and septum transversum
Each canal is lateral to the foregut and dorsal to the septum transversum
What structure is growing into the pericardioperitoneal canals that gives rise to membranous ridges in the lateral wall of each canal?
Lung buds
Growth of pleural cavities creates two layers in the body wall:
Outer layer forms thoracic wall, inner layer forms the pleuropericardial membranes
Which side of the diaphragm?
The right side closes before the left as the myoblast migrate into pleuroperitoneal membranes. This is likely due to the development of the large right lobe of the liver.
respiratory (laryngotracheal) diverticulum (lung bud)
A ventral outpouching of endodermal foregut that begins the development of the lungs.
What does the proximal end of the laryngotracheal diverticulum form
larynx and trachea
What does the distal end of the laryngotracheal diverticulum form?
The right and left primary bronchial buds
What is the embryological derivative of the lungs
Composite of endoderm and mesoderm tissues
What are the endodermal portions of the lung?
Epithelial cells of alveoli and mucosal lining of bronchi
What are the mesodermal components of the lung?
muscle and cartilage supporting bronchi, visceral pleura covering the lung
Tracheoesophageal septum
Formed from tracheoesophageal ridges (folds) that separates the respiratory and GI tract
Laryngeal orifice
a communication between the pharynx and the respiratory primordium.
Embryological derivative of epithelial lining of larynx
endoderm of lung bud
Laryngeal recanalization
Laryngeal ventricles develop and folds of mucous membrane become the vocal cords.
What does the epiglottis form from
Hypopharyngeal eminence
Innervation of the laryngeal muscles
Cranial nerve X, Vagus nerve
Differentiation of the endodermal lining of the laryngotracheal tube
differentiates into the epithelium and glands of the trachea and pulmonary epithelium
Secondary bronchial buds
3 on the right side and 2 on the left; these go to the lobes of the lung
Tertiary Bronchi
about 10 on each side, also known as segmental bronchi
Branching of bronchioles after tertiary bronchi
Bronchopulmonary segments, terminal bronchioles, respiratory bronchioles, terminal sacs (primitive alveoli), mature alveoli.
Major events in embryonic respiratory development period
26 days to 6 weeks, lung bud develops, branching of bronchopulmonary segments, trachea and larynx formed
Major events in pseudo glandular period
6-16 weeks, Formation of terminal bronchioles. All major elements of lung have formed except those involved in gas exchange
Major events in canalicular period
16-26 weeks, Terminal bronchiole divides into respiratory bronchioles, respiratory vasculature develops, lung epithelium differentiates into specialized cells, respiration is possible at the end of this period. There is a blood air barrier for gas exchange
Major events of saccular period
26-36 weeks, Respiratory bronchioles subdivide to produce terminal sac, type Ii pneumocytes secrete pulmonary surfactant, blood-air barrier is finished
Alveolar
36 weeks +, Alveoli and gas exchange structures mature
Which cells produce pulmonary surfactant
Type II alveolar cells
SP-B and SP-C
Hydrophobic proteins that play a major role in surface-active properties of surfactant
SP-A and SP-D
Hydrophilic proteins that are important for host defense, immunomodulation and surfactant clearance and metabolism
Esophageal Atresia
Blind esophagus
Tracheoesophageal Fistula
Abnormal connection between tracheal and esophageal lumen, results from failure of tracheoesophageal folds to completely fuse.
VACTERL Association
Vertebral anomalies, anal atresia, cardiac anomalies, tracheoesophageal fistula, Esophageal atresia, Renal anomalies, Limb anomalies
Most common type of TEF
Type C
Least symptomatic type of TEF
Type H
Diagnostic criteria for TEF
polyhydramnios+clinical presentation+chest x-ray
RDS cause
insufficient surfactant production
Causes of pulmonary hypoplasia
Oligohydramnios, CDH
Causes for oligohydramnios
renal agenesis, or premature rupture and leakage of amniotic fluid
Potter’s Sequence
various abnormalities resulting from oligohydramnios
Most common type of CDH
posterolateral Bochdalek hernia
Causes of CDH
defective formation and/or fusion of pleuroperitoneal membranes with the other three parts of the diaphragm
Aorticopulmonary Septum
Creates two outflow paths through aorta and pulmonary trunk
