Embriology Flashcards
Origin of epith of digestive tract + parenchyma of some glands
Endoderm
Origin of muscle walls of viscera + CT layers surrounding viscera
Mesoderm
Liver arises from
Liver bud
Liver bud protrudes into
Ventral mesogastrium
Ventral mesogastrium divides into
Gastrohepatic / lesser omentum
Falciform ligament
Gastrohepatic / lesser omentum connects
Stomach and liver
Falciform ligament connects
Liver to the ventral wall
Liver location
R side
Liver functions
Glycogen production
Albumin production
Protein metabolism
Bile secretion
Hematopoietic function (after embryonic splanchnic mesoderm)
Bile is stored in
Gallbladder
Gallbladder origin
Hepatic duct grows and gives it
Gallbladder is connected to the liver by
Cystic duct
Gallbladder reaches duodenum through
Common bile duct
Pancreas origin from
Ventral + dorsal pancreatic duct
They fuse and for the head, neck and body
Ventral pancreatic duct arises from
Common bile duct
Relation main pancreatic duct - duodenum
It opens through the common bile duct into the 2nd portion of the duodenum, so both hepatic and pancreatic secretions enter here to participate in digestion.
Accessory pancreatic duct origin
Dorsal pancreas duct that persist a persist as a little accessory pancreatic duct
Accessory pancreatic duct function
When the main pancreatic duct is blocked
Separation between the derivatives of the foregut and the derivatives from the midgut
Major duodenal papilla
Major duodenal papilla marks
Point where main pancreatic duct and bile duct drain into duodenum
Minor duodenal papilla
Where accessory pancreatic duct drains into the duodenum in case of blockage of the main one
Stomach formation
It rotates around its long axis 90º clockwise —> behind it appears ommental bursa / lesser sac
Post walls grow faster —> increased curvature on L side
Cardiac portion: downwards
Pyloric portion: upwards
Stomach is connected and attached by
Mesenteries
Liver arises within
Ventral mesogastrium
Pancreas and spleen arise within
Dorsal mesogastrium
Dorsal mesogastrium gives rise to
Greater omentum
Mesenteries definition
Double layer of peritoneum
Mesenteries function
Connects viscera to dorsal and ventral walls
Esophagus formation
From foregut ventral wall —> respiratory diverticulum that will be separated from esophagus by tracheoesophageal septum
Anomalies in esophagus formation
Tracheoesophageal fistulas —> prenatal: polyhydramnios / postnatal: regurgitation)
Incomplete recanalization (stenosis)
Congenital hiatal hernia —> stomach herniates into thoracic cavity
Midgut definition
Part of the gut tub that remains connected to the yolk sac after the folds progresses.
Connected to abdominal wall by dorsal mesentery through which arteries can access
Midgut location
Inferiorly to major duodenal papilla -> junction prox 2/3 - distal 1/3 of transverse colon
Disposition changes of the midgut
(Dorsal mesentery rotates along w/ structures)
5th week: U-shape loop has sup+inf limb & vitelline duct
6th week: midgut limb growth + not enough space = physiological herniation into umbilicus (90º rotation) —> sup limb to R (small intest loops), inf limb to L (large intest derivatives)
10th week: enough space -> physiolog hernia reduction —> inf limb also enters but rotates 180º
Anomalies of the midgut development
Malrotation
Meckel’s diverticulum - by persistence of vitelline duct
Umbilical hernia - by unproperly abd musculature closure
Omphalocele - by failure of reduction of physiolog herniat.
Gastroschisis - by incomplete closure of lat folds (viscera bathed by amniotic fluid)
Hindgut location
Begins just before L colic flexure/ splenic flexure
Ends in the cloacal membrane
Caudal portion of the hindgut =
Cloaca
Post to the cloaca is the
Allantois
Allantois is related to
Bladder and urogenital system
Hindgut is separated from allantois by
Urorectal septum
Urorectal septum definition
Mesoderm ridge that will form the perineum
Urorectal septum development
Will grow caudally and separate cloaca into
- ant: allantois
- post: rectum and anal canal
Will separate the cloacal membrane into
- urogenital membrane
- anal membrane
Cloacal membrane gives rise to
Proctodeum
Anal canal origins
- 1º 2/3 of anal canal —> from hindgut
- last 1/3 of anal canal -> from proctodeum (= ectoderm invagination)
Last portion of anal canal innervation and irrigation
Innervation: somatic
Irrigation: inf and middle rectal veins -> common iliac veins
Anal membrane rupture
8th week
Congenital anomalies of the hindgut
Incorrect development of urorectal septum
- imperforate anus
- rectovaginal fistula
- fistula ureters-rectum
- rectal atresia
Megacolon/ Hirschsprung disease
(non-proper migration of NCC during 4-5th week = no PS ganglia = no peristalsis = food accumulation = dilation)
