UNSW Embryology

RESPIRATORY SYSTEM
Embryology Home Page

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Page LinksIntroductionReading Computer Activities ObjectivesLearning activities Development Overview Pig OverviewTermsReferencesAbout Notes

Page 2 | Abnormalities | OMIM | Self Assessment Questions | Medline
Page 3 | Pig Stage 13/14
Page 4 | Human (St 22) Trachea | Human (st 22) Lungs
Page 5 | Selected Human highpower
Text only page | WWW Links

Introduction

Reading

  • Human Embryology (2nd ed.) Larson Ch6: p127-149
  • The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Ch11: p226-233
  • Before we Are Born (5th ed.) Moore and Persaud Ch12; p241-254
  • Essentials of Human Embryology Larson Ch6 p81-96
  • Human Embryology Fitzgerald and Fitzgerald Ch18 p113-118
  • Additional References- Selected, Lung Development, Respiratory Development
  • Search PubMed- Medline

Computer Activities

UNSW Embryology:

Embryo Images Unit:

Unit: Body Cavities

Objectives

  • Describe the development of the respiratory system from the endodermal and mesodermal components.
  • Describe the main steps in the development of the lungs.
  • Describe the development of the diaphragm and thoracic cavities.
  • List the respiratory changes before and after birth.
  • Describe the developmental aberrations responsible for the following malformations: tracheo - oesophageal fistula (T.O.F); oesphageal atresia; diaphragmatic hernia; lobar emphysema.

Learning activities

  • Summarise the changes in the respiratory system and the C.V.S. at birth.??
  • To discuss the main features of physiological maturation of the lung and the importance of this to fetal and newborn viability.
  • Examine the serial sections of human and pig with reference to the respiratory system.
  • Discuss the selected malformations; tracheo - oesophageal fistula (T.O.F.) diaphragmatic hernia and lobar emphysema giving special reference to the developmental aberrations causing the malformations to the individuals

Development of the Respiratory System

  • Week 4 laryngotracheal groove forms on floor foregut
  • Week 5 left and right lung buds push into the pericardioperitoneal canals (primordia of pleural cavity)
  • Week 6 descent of heart and lungs into thorax. Pleuroperitoneal foramen closes.
  • Week 7 enlargement of liver stops descent of heart and lungs.

Diaphragm- 5 elements contribute to the diaphragm

  • septum transversum- central tendon
  • 3rd to 5th somite- musculature of diaphragm
  • ventral pleural sac- connective tissue
  • mesentry of oesophagus- connective tissue around oesophasus and IVC
  • pleuroperitoneal membranes- connective tissue around central tendon

Blood Supply-

  • pulmonary system not "functional" until after birth
  • 6th aortic arch arteries generate pulmonary areries
  • veins drain into pulmonary vein then left atrium
  • branches from dorsal aorta generate bronchial arteries

Lung Histology-

  • 4 periods
    • 5-17 week pseudoglandular
    • 16-25 week canalicular
    • 24-40 week terminal sac
    • late fetal-8years alveolar
  • month 3-6 lungs appear glandular
  • end month 6 alveolar cells type 2 appear and begin to secrete surfactant
  • month 7 respiratory bronchioles proliferate and end in alveolar ducts and sacs

Pig Serial Sections

References

Respiratory Terms

  • atresia- obstruction.
  • eppiglottis- develops from hypobrachial eminence.
  • fistula- abnormal comunication.
  • hypopharyngeal eminence- fusion of 3rd pharyngeal arches, precursor of root of tongue.
  • laryngotracheal groove- forms on anterior (ventral) wall of pharynx, gives rise to larynx, trachea, respiratory tree.
  • larynx- lining from endoderm, cartilage from pharyngeal arch 4 and 6.
  • lung buds- primordia of lungs.
  • parietal pleura-outer lining of pleural cavity derived from epithelia of pericardioperitoneal canals from intraembryonic coelom.
  • pleural cavity- walls derived from pericardioperitoneal canals -> intraembryonic coelom ->coelomic spaces -> lateral mesoderm -> mesoderm.
  • pleuropericardial fold- restricts the communication between pleural cavity and pericardiac cavity, contains cardinal vein and phrenic nerve.
  • pleuroperitoneal membrane- forms inferiorly at transverse septum to separate peritoneum from pleural cavity.
  • septum transversum- mesoderm separating thoracic cavity and yolk sac, forms central tendon of diaphragm (and some of liver?).
  • stenosis- narrowing
  • surfactant- a detergent secreted by Type 2 alveolar cells between alveolar epithelium. Functions to lower surface tension, allowing lungs to remain inflated.
  • visceral pleura- inner lining of pleural cavity derived from contact epithelia with lung bud of pericardioperitoneal canals from intraembryonic coelom.

About Notes

  • These lecture notes from the Embryology course compiled and written by Dr Mark Hill.
  • Note Links to PubMed Medline Entries are copies of originals for computers without internet access. Computers with internet access can directly access the database.
  • Note that reference lists are only relevant to the date that the original search was carried out.

Links
Serial Sections Homepage
Human Homepage
Pig Homepage

m.hill@unsw.edu.au
Date Last Modified: 11/3/99
This site maintained by Dr M. Hill