Embryology

Respiratory System

• Week 4: Respiratory Diverticulum forms from ventral foregut.
• Week 5: Primary buds ENLARGE. Forming R/L Primary Bronchi.
• Further Development: 2ndary Bronchi subdivide to form Tertiary
• Wk 5 to 16 - Pseudoglandular Period - Further bronchial division, to form Terminal Bronchioles.
• Maturation - Canalicular Period, Terminal Sac Period, Alveolar Period

Cardiovascular System

• Week 3: Primary Heart Field - Establishment & Patterning
• Week 4: Formation and Positioning of Heart tube
• Formation of Cardiac Loop
• Day 23-28: Cardiac tube bends
• Sinus Venosus Development
• Day 27-37: Cardiac Septa Formation
• Defects: Most common: 1% Live Neonates. Often accompanied by other major defects

Foetal Circulation

• Sinus Venosus: Paired Veins L/R.
• Arterial
• Foetal
• Circulatory Changes (at Birth)