Embryology Notes
System by System

Development of the heart, great vessels, and foetal circulation — with all major congenital heart defects and their embryological basis.

• Heart tube formation and folding — weeks 3 to 4
• Septation of atria, ventricles, and outflow tract
• Foetal circulation and changes at birth
• VSD, ASD, TOF, PDA — embryological basis

Development of the lungs and airways — surfactant timing, respiratory distress syndrome, and tracheo-oesophageal defects.

• Lung bud development from foregut
• Surfactant production — timing and clinical significance
• Tracheo-oesophageal fistula types
• Congenital diaphragmatic hernia

Foregut, midgut, and hindgut derivatives — gut rotation, fixation, and the congenital anomalies that result from errors at each stage.

• Foregut, midgut, hindgut derivatives
• Gut rotation and malrotation
• Meckel’s diverticulum and its rule of 2s
• Hirschsprung disease — embryological basis

Neural tube development, brain vesicles, and neural crest cells — with all major neural tube defects and their clinical presentations.

• Neural tube formation and closure defects
• Spina bifida types — occulta, meningocele, myelomeningocele
• Brain vesicle development — primary and secondary
• Neural crest cell derivatives and syndromes

Pronephros, mesonephros, metanephros sequence — renal agenesis, horseshoe kidney, and urinary tract anomalies explained developmentally.

• Three kidney stages and their clinical relevance
• Ureteric bud and metanephric mesoderm interaction
• Renal agenesis — Potter sequence
• Horseshoe kidney and ectopic kidney

Sexual differentiation, Müllerian and Wolffian duct development — and the congenital anomalies that arise from errors in sex determination.

• Indifferent gonad — timeline and triggers
• Müllerian vs Wolffian duct derivatives
• Androgen insensitivity syndrome
• Cryptorchidism and hypospadias