UNSW Embryology

Respiratory Development

© Dr Mark Hill (2008)

Acknowledgements

Introduction

The respiratory system does not carry out its physiological function (of gas exchange) until after birth. The respiratory tract, diaphragm and lungs do form early in embryonic development.

Lung buds (stage 13)

Lungs (stage 22)

Fetal lung histology (Image: Lutz Slomianka, UWA Blue Histology)

   

In the head/neck region, the pharynx forms a major arched cavity within the phrayngeal arches. The lungs go through 4 distinct phases of development and late in foetal development respiratory motions and amniotic fliud are thought to have a role in lung maturation.

Development of this system is not completed until the last weeks of Fetal development, just before birth. Therefore premature babies have difficulties associated with insufficient surfactant (end month 6 alveolar cells type 2 appear and begin to secrete surfactant).

Page Links: Introduction | Reading | Computer Activities | ObjectivesLearning activities | Development Overview | Stage 13 Overview | Glossary | Respiratory Terms | References

Some Recent Findings

Shu W, Lu MM, Zhang Y, Tucker PW, Zhou D, Morrisey EE. Foxp2 and Foxp1 cooperatively regulate lung and esophagus development. Development. 2007 May;134(10):1991-2000. (More? Respiratory Molecular Development)

Cardoso WV, Lu J. Regulation of early lung morphogenesis: questions, facts and controversies. Development. 2006 May;133(9):1611-24.

"During early respiratory system development, the foregut endoderm gives rise to the tracheal and lung cell progenitors. ....Here, we review early stages in lung development and highlight questions and controversies regarding their molecular regulation."

Harris KS, Zhang Z, McManus MT, Harfe BD, Sun X. Dicer function is essential for lung epithelium morphogenesis. Proc Natl Acad Sci U S A. 2006 Feb 14;103(7):2208-13.

"DICER is a key enzyme that processes microRNA and small interfering RNA precursors into their short mature forms, enabling them to regulate gene expression. Only a single Dicer gene exists in the mouse genome, and it is broadly expressed in developing tissues. Dicer-null mutants die before gastrulation.......leading us to propose that Dicer plays a specific role in regulating lung epithelial morphogenesis independent of its requirement in cell survival."

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
Historic Heart and Lungs

Objectives

Computer Activities

UNSW Embryology: Pig Stage 13/14 Overview | Stage 13/14 Embryo (Pig) | Stage 22 Embryo (Human) | Selected Stage 22 Human high power (st22) | Early Fetal (wk10) | Systems (Pig, Respiratory) | Read Respiratory Development- Selected Review 1999 Abstracts

Embryo Images Unit: Unit: Body Cavities

Learning activities

Stage 13/14 Cross Sections

Lung 2

Note: Click on the small cross-section extract to view entire section.

Developmental Overview

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.

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.

Lung Development 4 histological periods

Diaphragm 5 elements contribute to the diaphragm (More? Respiratory - Diaphragm | Musculoskeletal System - Muscle)

Blood Supply

References

Reviews

Cardoso WV, Lu J. Regulation of early lung morphogenesis: questions, facts and controversies. Development. 2006 May;133(9):1611-24.

Warburton D, Bellusci S, De Langhe S, Del Moral PM, Fleury V, Mailleux A, Tefft D, Unbekandt M, Wang K, Shi W.    [See Related Articles] Molecular mechanisms of early lung specification and branching morphogenesis. Pediatr Res. 2005 May;57(5 Pt 2):26R-37R.

Kumar VH, Lakshminrusimha S, Abiad MT, Chess PR, Ryan RM.    [See Related Articles] Growth factors in lung development. Adv Clin Chem. 2005;40:261-316. Review.

Groenman F, Unger S, Post M.    [See Related Articles] The molecular basis for abnormal human lung development. Biol Neonate. 2005;87(3):164-77. Epub 2004 Dec 9. Review.

Chinoy MR.    [See Related Articles] Lung growth and development. Front Biosci. 2003 Jan 1;8:d392-415. Review.

[No authors listed]    [See Related Articles] Surfactant replacement therapy for respiratory distress syndrome. American Academy of Pediatrics. Committee on Fetus and Newborn. Pediatrics. 1999 Mar;103(3):684-5.

O'Rahilly R, Tucker JA.    [See Related Articles] The early development of the larynx in staged human embryos. I. Embryos of the first five weeks (to stage 15). Ann Otol Rhinol Laryngol. 1973 Sep-Oct;82:1-27.

Selected Lists of References from PubMed March 1999 search results are available for Department of Anatomy computers without internet access. Computers with internet access can search from either Selected Research Articles and Reviews | Respiratory/development/review/5year limit" | "Lung development/review/5year limit"

Search PubMed Now: term= lung+development | diaphragm+development | pulmonary+development (Requires internet connection)

Glossary of Terms

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Respiratory Terms

Quick Links

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