UNSW Embryology

RESPIRATORY SYSTEM

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DEVELOPMENTAL ABNORMALITIES

Oesophageal Atresia
Lobar Emphysema
Hyaline Membrane Disease
Diaphragmatic Hernia
Azygos Lobe

TRACHEO-OESOPHAGEAL FISTULA (OESOPHAGEAL ATRESIA)

OMIM Database Entry- Tracheosophageal Fistula

OESOPHAGEAL ATRESIA- with or without tracheo-oesophageal fistula

International Classification of Diseases code 750.3

Australian national rate (1982-1992) 2.5 - 3.6 /10,000 births.

Of 847 infants 9.9% were stillborn and 20.4% liveborn died during neonatal period.

3 times as common in twin births than singleton.

Congenital Malformations Australia 1981-1992 P. Lancaster and E. Pedisich ISSN 1321-8352

Summary

Oesophageal atresia as suggested by

(a) Polyhydramnios
(b) Reflex increase in salivation
(c) Holdup of the catheter confirmed by the X-ray appearance of the dilated blind proximal oesophagus. The fistula is confirmed by the presence of gas in the intestines.

Management

1. Operative closure of the trachea end of the fistula.
2. Restoration of the continuity of the oesophagus
N.B. This is a serious malformation with significant risk of mortality

Associated Malformations

(a) Stratified squamous epithelium and columnar epithelia (mixtures of tracheal and oesophageal epithelial) are found in the trachea and oesophagus.
(b) This often occurs as one of a complex of malformations in a child. The origin is in early embryogenesis and often associated with
(i) cloacal malformation
(ii) cardiac septal defects
(iii) renal malformations

Questions

(a) The failure of what embryological process might give rise to this malformation?
(b) Why is there almost invariable association of tracheo oesophageal fistula with polyhydramnios?

(c) Why is there an early onset of pneumonia if the malformation is unrecognised?

(d) How might the defect possibly be corrected?

LOBAR EMPHYSEMA (Overinflated lung)

OMIM Database Entry- Lobar Emphysema
1. There is an overinflated left upper lobe
2. There is a collapsed lower lobe
3. The left lung is herniating across the mediastinum

Description of lesion - there is a congenital deficiency of cartilage in the left upper lobe bronchus. The anatomical nature of the lesion was demonstrated by autopsy specimens and usually reveals no abnormality other than cartilage deficiency throughout the lobe.

Summary

(a) Respiration is normal at first
(b) Once distress occurs overinflation is rapidly progressive and may kill by asphyxia.
(c) This is called Lobar Emphysema due to congenital broncho-malacia (soft bronchi).

Management

The affected lobe must be resected.

RESPIRATORY DISTRESS SYNDROME IN THE NEWBORN (Hyaline Membrane Disease)

Management

1. R.D.S. is normally treated conservatively with 02, intravenous bicarbonate and general supportive measures but the mortality rate is high in more premature infants. At autopsy the principle change to be seen is an eosinophilic hyaline membrane filling the alveoli.
2. If the child is treated with constant positive airway pressure this increases arterial 02 tension and helps prevent the collapse of alveoli which deficient surfactant otherwise causes. This increases the functional residual capacity of the lungs. This support system is effective in the nearly mature infants but the more premature still have a high mortality rate.

CONGENITAL DIAPHRAGMATIC HERNIA

Failure of the pleuroperitoneal foramen (foramen of Bochdalek) to close allows viscera into thorax. Intestine, stomach or spleen can enter the pleural cavity, compressing the lung.

International Classification of Diseases code 756.6

Australian national rate (1982-1992) 2.1 - 3.8 /10,000 births.

Congenital Malformations Australia 1981-1992 P. Lancaster and E. Pedisich ISSN 1321-8352

AZYGOS LOBE

Common condition (0.5% of population). The right lung upper lobe expands either side of the posterior cardinal.

Management

Condition is generally harmless.

Australian Statistics 1981-1992

About Data

Data shown as a % of all Major Abnormalities based upon published statistics using the same groupings as CMA 81-92.

You can also see:

all the statistical data as graphs

List of all Minor Abnormalities

OMIM Database Online Mendelian Inheritence in Man Database. OMIM

Internet Search this database with the keyword "lung" or the above abnormality names.

Note: This database is an external link, not accessible from some computers in the School of Anatomy.
A List of the 570 entries found, searching for "lung" is available for these computers.

Enter one or more search keywords:
To Search all fields, leave the following boxes unchecked. To narrow your search to certain specific fields, check the boxes next to those fields' names. See Query Help for other ways to search.
Title: OMIM Number: Allelic Variants: Text: References: Clinical Synopsis: Gene Map Disorder: Contributors:
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Self Assessment Questions

How is the trachea formed and what are the basic derivations of the lung?

How does the thoracic cavity develop?

What processes occur during the maturation of the lung in the fetus?

What is a tracheo-oesophageal fistula? How does this affect the amount of amniotic fluid present?

How is the larynx formed?

PubMed Database

Online Medline Database PubMed- Medline

National Library of Medicine (US) search service to access the 9 million citations in MEDLINE and Pre-MEDLINE (with links to participating on-line journals), and other related databases.

Internet Search this database or use the form below with the keyword or related topics. You can also restrict to reviews or by date published.

Note: This database is an external link, not accessible from some computers in the School of Anatomy.

A Selected List of References from March 1999 search results for "Respiratorydevelopment/review/5year limit" and "Lung development/review/5year limit" is available for these computers.

Search Field: Mode:

PubMed

Respiratory Terms

atresia- obstruction.

eppiglottis- develops from hypobrachial eminence.

laryngotracheal groove- forms on anterior (ventral) wall of pharynx, gives rise to larynx, trachea, respiratory tree

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

Lecture notes from the Anat 3311 1997 Science Embryology course compiled and written by Dr Mark Hill. Some notes derived from historic class notes.
Note Links to OMIM Entries are copies of originals for computers without internet access. Computers with internet access can directly access the database.

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