Embryology Flashcards
How does fetal lung development begin
ventral outpouching of the endodermal foregut called the respiratory (laryngotracheal) diverticulum (lung bud) –> day 22
The proximal end of the respiratory diverticulum forms the…
Larynx and trachea
The lung is comprised of what types of tissue
endoderm and mesoderm
The endoderm of the respiratory diverticulum gives rise to…
mucosal lining of the bronchi and to the epithelial cells of the alveoli
Mesoderm in the lung forms…
muscle and cartilage supporting the bronchi and the visceral pleura covering the lung
tracheoesophageal septum forms from…
fusing of the two tracheoesophageal ridges (folds)
dorsal foregut becomes…
ventral foregut becomes…
esophagus
trachea and lung buds
Tracheo-esophageal fistula (TEF) results from…
incomplete fusion of the tracheoesophageal folds that results in a failure of the foregut to separate completely into trachea and esophagus.
Trachea develops from …
proximal part of the respiratory diverticulum
The cartilage, connective tissue, and muscles of the trachea are derived from…
splanchnic mesenchyme surrounding the laryngotracheal tube.
Number of lung lobes in each for developing embryo
3 in right, 2 in left
When is the limited age of viability and why?
22-23 weeks gestation. Respiration is possible only after the blood-air barrier is esblished and the gas exchange can be performed
complex mixture of phospholipids and proteins in maturing alveoli
Pulmonary surfactant (secreted by alveolar type II cells)
The respiratory distress syndrome of premature infants is caused by
inadequate production of surfactant
Potter sequence
a spectrum of abnormalities . These include deformed limbs; wrinkly, dry skin; and an abnormal facies (in this context, facies means “facial appearance”) consisting of wide-set eyes with infraorbital skin creases, beak nose, recessed chin, and low-set ears.
The intraembryonic coelom is partitioned by
A pair of pleuropericardialmembranes
A pair of pleuroperitoneal membranes
When the intraembryonic coelom forms, the lateral mesoderm divides into:
somatic (parietal) and splanchnic (visceral) mesoderm
Each pericardioperitoneal canal lies:
- lateral to the foregut(future esophagus)
- dorsal to septum transversum(part of the future diaphragm).
4 embryonic sources of diaphragm
central tendon of the diaphragm is made of what tissue
mesodermal mass in the cervical region of the embryo
Fusing of what two tossues completes the partition between thoracic and abdominal cavities
dorsal mesentery of esophagus and septum transversum
Congenital Diaphragmatic Hernia (CDH) is caused by what
failure of pleuroperitoneal foldsto develop or to fuse with other components of diaphragm (usually posterolateral on left side)
Blood vessel formation begins during week … in the extraembryonic mesoderm of the yolk sac, connecting stalk and chorion.
3
Primary embryonic arteries
paired dorsal aorta
intersegmental arteries between somites
aortic arch arteries
Primary embryonic venous system
Cardinal venous system
Placenta blood flow
Blood enters embryo through 1 umbilical vein and returns to mother through 2 umbilical arteries
Circulation of yolk sac is primary through …
Vitelline veins
Caudally, the dorsal aortae fuse to form
Descending aorta
From where do pharyngeal arch arteries arise?
aortic sac
How are the aortic sac and dorsal aortae connected
aortic arches
What is the function of umbilical arteries
Links dorsal aortae to capillaries of chorionic villi (develop in connecting stalk)
Name gastrointesinal arteries
Celiac (caudal)
Superior
Inferior mesenteric (rostral)
Form from vitalline, off of descending aorta
What does the aortic sac later give rise to
Brachiocephalic artery and ascending aorta
What does the third aortic arch become
Common carotid arteries
Proximal internal carotid arteries (rest by doersal aorta)
From what do external carotids form
They sprout from the internal carotids
Left fourth aortic arch forms…
Right fourth aortic arch forms…
Part of aortic arch
Proximal right subclavian artery
Left sixth aortic arch becomes
Right sixth aortic arch becomes
Left pulmonary artery and ductus arteriosus
Right pulmonary artery
The recurrent laryngeal nerves hook around which aortic arches
sixth
3 paired veins that drain into sinus venosus
vitelline veins (low oxygen, yolk sac)
Umbilical veins (placenta, high oxygen)
Common cardinal veins (low oxygen, embryonic body)
What veins drain cranial portion of embryo
anterior cardinal veins
Anterior cardinal veins join to form what? Function?
Left brachiocephalic vein, shunts blood from left to right AC vein
What forms the superior vena cava
right anterior cardinal and right common cardinal veins
Supracardinal veins form from
Posterior cardinal veins
Azygous vein forms from
Right supracardinal vein
Left supracardinal vein forms
Hemizygous vein
Accessory hemizygous vein
Function of ductus venosus
allows most of the blood from the placenta to bypass the liver (by flowing directly into IVC)
Portal vein is derived from
vitelline veins
Left umbilical vein becomes …
Umbilical vein
Where does the heart begin to develop
The cardiogenic region
Angioblastic cords form from what tissue
Mesoderm
angioblasticcords canalize (hollow out) to form
two parallel endocardial heart tubes
Splanchnic mesoderm becomes…
Somatic mesoderm becomes…
Visceral pericardium
Parietal pericardium
Flow of blood through primitive heart
Dextrocardia cause
- Embryonic heart tube bends to the left instead of to the right
- Heart is displaced to the right
What is sinus venarum
Part of the developing atrium where the sinus venosus is incorporated into
How do pulmonary veins form
During week 4, the primitive atrium sprouts a pulmonary vein that divides to produce a total of 4 pulmonary veins that grow toward the lungs where they anastomose with veins developing in the mesoderm around the bronchial buds.
Four sets of partitions in developing heart seperate:
1) the atria from the ventricles
2) the right and left atria
3) the right and left ventricles
4) the pulmonary trunk and ascending aorta
What is the atrioventricular canal
a large single passageway between the primitive atrium and the primitive ventricle
Ebndocardial cusions do what?
Theendocardial cushions grow toward one another and fuse medially, dividing the AV canal into a right and left atrioventricaropenings.
What is the foramen primum
opening between the septum primumand the endocardial cushions.
Order of atrial spetation
- Foramen primum
- Septum primum
- Foramen secundum
- Septum secundum
- Foramen Ovale
- Fossa Ovalis
What forms the partition between aorta and pulmonary trunk
aorticopulmonary septum
The aorticopulmonary septum develops from what
Truncal ridges and bulbar ridges (neural crest cells)
