Development of Respiratory System • It begins at the end of third week by formation of endodermal laryngo-tracheal groove at floor of pharynx caudal to hypobranchial eminence. • Laryngotracheal tube is separated from foregut by formation of tracheo- esophageal septum. This tube elongates till the thorax. • Upper part of the tube forms the mucus membrane of larynx while lower part form mucus membrane of trachea and bronchi. • The lower end of the tube will divides to form 2 lung buds. • Surrounding mesoderm will form muscles and cartilages of larynx and trachea. Dr. Sherif Fahmy
9
Embed
Development of Respiratory System (Special Embryology)
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Development of Respiratory System• It begins at the end of third week by formation of
endodermal laryngo-tracheal groove at floor of pharynx caudal to hypobranchial eminence.
• Laryngotracheal tube is separated from foregut by formation of tracheo-esophageal septum. This tube elongates till the thorax.
• Upper part of the tube forms the mucus membrane of larynx while lower part form mucus membrane of trachea and bronchi.
• The lower end of the tube will divides to form 2 lung buds.
• Surrounding mesoderm will form muscles and cartilages of larynx and trachea.
Dr. Sherif Fahmy
Formation of Lungs• Each lung bud divides into 3 branches, but on left
side one of the branches disappears. Right lung has 3 lobes, left lung has 2 lobes.
• Each branch of the lung bud divides repeatedly to form bronchioles and lastly alveoli.
• Blood vessels are formed from surrounding mesoderm.
• Lung invades pleura from medial aspect, so pleura surrounds lung by 2 layers.
• Expansion of lung occurs after birth when the baby takes his first inspiration
Dr. Sherif Fahmy
2 lingual swellings
Tuberculum impar
Foramen ceacum
Copula
Hypobranchial eminence
Laryngeo-trachial groove
Pharynx
Respiratory diverticulum
Dr. Sherif Fahmy
Laryngeo-tracheal duct
esophagusDr. Sherif Fahmy
Laryngo-tracheal duct
Foregut Tracheo-esophageal ridges
Lung buds
Dr. Sherif Fahmy
Dr. Sherif Fahmy
Congenital Anomalies• 1- Tracheo-oesphageal fistula: Due to
incomplete formation of tracheo-oesophageal septum.• 2- variations in branching of lung bud:
Leads to extra or missed lobe and may be missed lung.• 3- Congenital cyst.• 4- Esophageal atresia.• 5- Respiratory distress syndrom.