Development and teratology of digestive system. Anna Mac Gillavry 04.03.2024 • Primitive gut formation results from the lateral folding of the embryo • Foregut, midgut and hindgut • (Yolk sac, allantois) Hindgut T.W. Sadler, Langman's medical embryology, 14th edition Diaphragm Bare area of liver Falciform ligament Umbilical vein (carries oxygenated blood to embryo) Extraembryonic coelom Lesser omentum I_ Hepatoduodenal ligament Hepatogastric ligament , Dorsal mesogastrium Midgut loop Dorsal pancreatic bud Celiac artery — Gallbladder Dorsal aorta Superior mesenteric artery Free edge of ventral mesogastrium Peritoneal cavity (former intraembryonic coelom) Inferior mesenteric artery K. Moor, Before we are born, 10th edition Esophagus 4th week Foregut Tracheoesophageal septum Respiratory diverticulum — Pharynx - Trachea Lung buds c i I Esophagus T.W. Sadler, Langman's medical embryology, 14th edition Stomach Two rounds of rotation: Dorsal surface Posterior surface 1. 90° clockwise along the longitudinal axis Right-vagus nerve Right LLeft border vagus nerve Ventral surface Posterior gastric nerve Left border Anterior gastric nerve Anterior surface Desarrollo de los Óreanos Abdominales I Concise Medical Knowledge (lecturio.com) 2. anteroposterior axis T.W. Sadler, Langman's medical embryology, 14th edition Dorsal mesogastrium Small vacuoles Stomach Lesser omentum T.W. Sadler, Langman's medical embryology, 14th edition T.W. Sadler, Langman's medical embryology, 14th edition Esophagus: - esophageal atresia and/or tracheoesophageal fistula -polyhydramnios - esophageal stenosis - congenital hiatal hernia Trachea Bifurcation ! Proximal blind-Pyr end part of esophagus -Tracheoesophageal fistula Distal part of esophagus B Communication of esophagus i with trachea Stomach: - pyloric stenosis (1 in 150 males, 1 in 750 females) - develops during fetal life, however, can develop as a result of postnatal exposure (e.g. erythromycin) T.W. Sadler, Langman's medical embryology, 14th edition https://www.neim.org/nal01/home/literatum/publisher/mms/iournals/content/neim/20 2017.377.issue-24/ nejmicml614216/20180122/images/img_xlarge/nejmicml614216_fl.jpeg Development of the liver and pancreas Major papilla' pancreatic duct Ventral pancreatic duct A B T.W. Sadler, Langman's medical embryology, 14th edition Development of the pancreas Bile duct Dorsal pancreatic bud Opening of bile and Accessory pancreas pancreatic ducts pancreatic duct E F G K. Moor, Before we are born, 10th edition Duodenum: - duodenal stenosis/atresia - results from incomplete recanalization; affects 20-30% of patients with Down syndrome, 20% of premature neonates polyhydramnios „Doble-Bubble" = stomach and proximal duodenum K. Moor, Before we are born, 10th edition Liver - birth deffects are rare: Accessory hepatic ducts - usually asymptomatic, in 5% of population Gallbladder duplication - usually asymptomatic https://www.researchgate.net/publication/342134005_Prenatal_u ltrasound_ diagnosis_of_duplication_gallbladder_a_multicenter_study Extrahepatic biliary atresia (1/15000 in US, however, higher rates in East Asia) - 15-20% has a potent proximal duct and fixable defect, the rest requires the liver transplant; symptoms: neonatal jaundice; Kasai procedure (hepatoportoenterostomy) -> liver transplant!!! Intrahepatic biliary duct atresia/hypoplasia (1/100000) Pancreas: Annular pancreas Accessory pancreatic tissue Accessory spleens - in 10 % of population A newborn patient with both annular pancreas and Meckel's di... : Medicine (lww.com) Development of the midgut T.W. Sadler, Langman's medical embryology, 14th edition 6th - 10th week https://youtu.be/AscKR_cQExY Body wall defects Gastroschisis (3,5/10000) - most common in infants from thin women under 20; usually not associated with chromosomal abnormalities and other severe defects, thus the mortality rate is low (unless associated with volvulus) Omphalocele (2,5/10000) up to 25 % mortality rate https://wwwTesearchgate.net/publication/270909178_Gastroschisis_Arteratal_Sonographic_Predictors_of_Adverse_Neonatal_Outcome Omphalocele I Childrer's Hospital of Philadelphia (chop.edul Vitelline duct abnormalities Meckel or ileal diverticulum - in 2 to 4 % of people, 3-5 times more prevalent in males (inflammation symptoms mimic those of appendicitis) Enterocystoma or vitelline cyst Umbilical or vitelline fistula Meckel diverticulum Umbilicus Ileum Vitelline cyst I Vitelline fistula B IY A newborn patient with both annular pancreas and Meckel's di... : Medicine (lww.com) Vitelline ligament Vitelline ligaments T.W. Sadler, Langman's medical embryology, 14th edition Gut rotation defects Left-sided colon - colon and cecum are the first to return from the umbilical cord cavity as the result of only 90° rotation Reversed rotation of the intestinal loop Duplications of intestinal loops and cysts Gut atresias and stenoses - Most occur in duodenum, fewest in the colon, equal number in jejunum and ileum; in 50 % of cases a region of bowel is missing completely, in 20 % cases the fibrous cord is present; stenoses represent only 5 % of cases Apple peel atresia -10 % of atresias: in the proximal jejunum, intestine is short, portion distal to the lesion coiled around remanent of mesenteries Hindgut Hindgut derivatives: - Left third of the transverse colon, descending colon, sigmoid colon, rectum, superior part of the anal canal - The epithelium of the urinary bladder and most of the urethra!!! Cloaca Phallus Hindcut Urorectal septum Anal p L Urorectal saplurn AJIantois Mesanchyrna Urorectal septum Hindgut Infolding of ^ cloaca! wall Level of sedion ß. Urogenital sinu Uroradal septum infolding o' laiaral wall of cloaca Rectum Level of section D, □1 Developing Uragenilal membránu ui nary bladder Urorectal seplum Rectum Anal canal Anal pil Urogenital sinus Urorectal septum Perineum 'Rectum p Level of section F, K. Moor, Before we are born, 10th edition Anal membrane Congenital megacolon (Hirschsprung disease) - 1/5000, males are affected 4 times more often than females Imperforate anus -1/5000 more common in males than females Anorectal birth defects - High vs. Low (rectum ends superior or inferior to the puborectalis muscle respectively) Low: anal agenesis, with or without fistula anal stenosis membranous atresia of anus High: anorectal agenesis, with or without fistula (2/3 of anorectal defects) rectal atresia Transition Zone in Hirschsprung's Disease I NEJM