Embryology and Foetal Development

Question 1

Describe the cardiovascular development of the foetus

Answer 1

The heart is the first thing to develop and foetal circulation is different to circulation ex-utero.

• Blood enters foetus through umbilical veins
• Then through liver (bypasses it) and ductus venosus into the IVC
• From right atrium to left atrium through foramen ovale
• Ductus arteriosus allows oxygenated blood to go from pulmonary artery to aorta.

Question 2

Describe the CNS development of the foetus

Answer 2

• One of the first things to develop
• Starts as neural plate, folding into a tube and then closing
• If neural tube doesn’t close, neural tube defects

Question 3

Describe the respiratory development of the foetus

Answer 3

• Starts to form at 3-7 weeks
• Full airway and vascular tree developed at 20 weeks
• Epithelial cells differentiate at 26 weeks
• Surfactant starts to be produced at 30 weeks
• Mature at 34-36 weeks

Question 4

Describe the alimentary development of the foetus

Answer 4

• Primitive gut present at 4 weeks
• Physiological hernia at 5-6 weeks
• Re-enters abdomen at 12 weeks

Question 5

Describe the renal and urinary development of the foetus

Answer 5

• Starts to develop at 3 weeks
• Fully formed at 32-34 weeks
• Full maturation continues after birth

Question 6

Describe the skin development of the foetus

Answer 6

• Single layer ectoderm at 4 weeks
• Begins to differentiate at 6 weeks
• Epithelium stratified at 16-20 weeks
• Hair follicles develop at 12-16 weeks
• Lanugo hair at 24 weeks

Question 7

Describe the haematological and immunological development of the foetus

Answer 7

• At 8 weeks, haematopoiesis by liver
• At 20 weeks, all by bone marrow
• Immune development at 12-14 weeks

Question 8

Describe the endocrine development of the foetus

Answer 8

• In place majorly by 12 weeks
• Testosterone at 17-21 weeks
• Thyroxine at 10-12 weeks

Question 9

Describe the development and function of the amniotic fluid

Answer 9

• Develops progressively over the 38 weeks
• Mainly foetal urine
• Starts to drop after 40 weeks, dramatically (unknown reasons)

Functions:

• Protect foetus from mechanical injury
• Permit movement of foetus while preventing contracture
• Prevent adhesions between foetus and amnion
• Permit foetal lung maturity