Embryology Of Fore Gut Flashcards
The GI tract is the main organ system derived from the ——— germ layer.
▪ This germ layer covers the ventral surface of the embryo and forms the —- of the yolk sac.
▪ With development and growth of the brain vesicles, the embryonic disc begins to fold ——.
The GI tract is the main organ system derived from the endodermal germ layer.
▪ This germ layer covers the ventral surface of the embryo and forms the roof of the yolk sac.
▪ With development and growth of the brain vesicles, the embryonic disc begins to fold cephalocaudally.
The folding is most pronounced in the regions of the — and —, where they form head and tail fold
▪ In the anterior part, the endoderm forms the —-; in the tail region, it forms the ——.
The folding is most pronounced in the regions of the head and tail, where they form head and tail fold
▪ In the anterior part, the endoderm forms the foregut; in the tail region, it forms the hindgut.
The part between foregut and hindgut is the ——. The midgut temporarily communicates with the yolk sac by way of a broad stalk, the ——-
▪ At its cephalic end, the foregut is temporarily bounded by an ectodermal-endodermal membrane called the —— membrane.
The part between foregut and hindgut is the midgut. The midgut temporarily communicates with the yolk sac by way of a broad stalk, the vitelline duct
▪ At its cephalic end, the foregut is temporarily bounded by an ectodermal-endodermal membrane called the buccopharyngeal membrane.
In the —- week, the buccopharyngeal membrane ruptures, establishing an open connection between the oral cavity and the primitive gut
▪ The hindgut also terminates temporarily at an ectodermal-endodermal membrane- the —- membrane, which breaks down in the ——week to create the opening for the anus.
In the 4th week, the buccopharyngeal membrane ruptures, establishing an open connection between the oral cavity and the primitive gut
▪ The hindgut also terminates temporarily at an ectodermal-endodermal membrane- the cloacal membrane, which breaks down in the 7th week to create the opening for the anus.
Extent of Foregut:
▪ Foregut starts from the —— and terminates at the level of ——— (the point where —— duct opens into —-)
Extent of Foregut:
▪ Foregut starts from the Oral cavity and terminates at the level of Ampulla of Vater (the point where common bile duct opens into Duodenum)
Gut-associated organs begin to form as buds from the ——-: (e.g., thyroid, lung, liver, pancreas)
Midgut opening to the yolk sac progressively ——
Gut-associated organs begin to form as buds from the endoderm: (e.g., thyroid, lung, liver, pancreas)
Midgut opening to the yolk sac progressively narrows
By the end of the first month:
The —— bulge is visible, ——pancreas has begun to bud
Connection of the midgut to the yolk sac is reduced to a ——-
By the end of the first month:
The stomach bulge is visible, Dorsal pancreas has begun to bud
Connection of the midgut to the yolk sac is reduced to a yolk stalk
A respiratory diverticulum develops from the —— of the foregut, divides the foregut into two parts:
▪ Part cranial to diverticulum - ——-
▪ Part caudal to diverticulum - ——-
A respiratory diverticulum develops from the floor of the foregut, divides the foregut into two parts:
▪ Part cranial to diverticulum - primitive pharynx
▪ Part caudal to diverticulum - foregut proper
List the derivatives of fore gut
Pharynx
Lower respiratory system
Oesophagus
Stomach
Proximal part of duodenum
Liver and biliary tree
Pancreas
Gut tube proper. Derivatives
Of gut tube
Fore :
Gut
Mid gut:
Hind gut:
Gut tube proper. Derivatives
Of gut tube
Fore : pharynx. Thyroid
esophagus. Parathyroid
stomach. Tympanic cavity
proximal duodenum. Trachea
Bronchi
Lungs
Liver,
gallbladder,
pancreas
Mid gut:distal duodenum
To right half of transverse
Colon
Hind gut:left half of. Urinary
Transverse colon. Bladder
To anus
The foregut derivatives except the pharynx, lower respiratory tract and most of esophagus are supplied by the ——— - the artery of the foregut
The foregut derivatives except the pharynx, lower respiratory tract and most of esophagus are supplied by the Celiac trunk- the artery of the foregut
Development of the Esophagus
▪ Esophagus develops from the foregut immediately caudal to the ——-
▪ The ——— septum separates it from the developing trachea
Development of the Esophagus
▪ Esophagus develops from the foregut immediately caudal to the primitive pharynx
▪ The tracheo-esophageal septum separates it from the developing trachea
Growth of
▪ Up to the —- week it is very short.
▪ Then, it elongates rapidly due to the descent of developing —- and —-.
▪ By the —- week it reaches its final position.
▪ Its lumen is completely or partially obliterated due to proliferation of its ——.
Growth of
▪ Up to the 4th week it is very short.
▪ Then, it elongates rapidly due to the descent of developing heart and lungs.
▪ By the 7th week it reaches its final position.
▪ Its lumen is completely or partially obliterated due to proliferation of its epithelial lining.
Duodenum
▪ The epithelial cells proliferate and obliterate the lumen (partly or completely) but ———-
▪ Recanalization normally occurs by the end of the —— period (—- wk)
▪ Failure of proper recanalization leads to narrowing of the lumen (also called—-)
▪ The epithelial cells proliferate and obliterate the lumen (partly or completely) but temporarily
▪ Recanalization normally occurs by the end of the embryonic period (8th wk)
▪ Failure of proper recanalization leads to narrowing of the lumen (stenosis)
▪Re-canalization of the oesophagus–errors in this process lead to ——-
▪Re-canalization –errors in this process lead to esophageal stenosis
▪ Epithelium & glands:
Derived from —-
▪ Striated muscles (mainly in the —-):
Derived from the ——-
▪ Smooth muscles (mainly in the —-):
Derived from the surrounding ——-
▪ Epithelium & glands:
Derived from endoderm
▪ Striated muscles (mainly in the superior third):
Derived from the mesenchyme in the caudal pharyngeal arches
▪ Smooth muscles (mainly in the inferior third):
Derived from the surrounding splanchnic mesoderm
Congenital malformations of
Esophagus
▪ Errors in forming the esophagotracheal septa and/or re-canalization- ———- and/or ——-, respectively.
▪ Atresia of Esophagus prevents the normal passage of amniotic fluid into the intestinal tract
leading to (———- accumulation of excess fluid in the amniotic sac)
▪ Short esophagus resulting in ——
Congenital malformations of
Esophagus
▪ Errors in forming the esophagotracheal septa and/or re-canalization- tracheoesophageal fistulas and/or esophageal atresia, respectively.
▪ Atresia of Esophagus prevents the normal passage of amniotic fluid into the intestinal tract
leading to (Polyhydroamnios)- accumulation of excess fluid in the amniotic sac
▪ Short esophagus resulting in hiatal hernia
▪Region of foregut just caudal to lung bud develops into ——
▪Endodermal lining is ——and proliferates such that the lumen is obliterated; patency of the lumen established by
▪Region of foregut just caudal to lung bud develops into esophagus –
▪Endodermal lining is stratified columnar and proliferates such that the lumen is obliterated; patency of the lumen established by
▪Region of foregut just caudal to lung bud develops into ——
▪Endodermal lining is ——and proliferates such that the lumen is obliterated; patency of the lumen established by
▪Region of foregut just caudal to lung bud develops into esophagus –
▪Endodermal lining is stratified columnar and proliferates such that the lumen is obliterated; patency of the lumen established by