Lecture 5: lung development

Question 1

embryonic stage

Answer 1

22 dyas- 6/8 weeks

-respiratory diverticulum forms

Question 2

pseudoglandular stage

Answer 2

6 weeks-16 weeks

-branching to from terminal bronchioles

Question 3

canalicular stage

Answer 3

16 weeks-26 weeks

-respiratory bronchioles form

Question 4

terminal sac stage

Answer 4

26 weeks- birth

-mature capillary- epithelium interface

Question 5

alveolar stage

Answer 5

~32 weeks-birth/postnatal

-increase in respiratory bronchioles and alveoli

Question 6

embryonic stage

endoderm derived epithelium

Answer 6

gives rise to epithelium lining the larynx and trachea, bronchi, bronchioles proximally

Question 7

embryonic stage

condensation of splanchnic mesoder

Answer 7

gives rise to cartilage, music , and connective tissue components, vascular network

Question 8

tracheoesophageal septum

Answer 8

develops and divides the trachea and lung buds from the esophagus
-initially in open communication with the foregut

Question 9

esophageal atresia with tracheoesophageal fistula

Answer 9

• fistula above atretic esophageal segment
• fistula below atretic esophageal segment
• fistula above and below the atretic esophageal segment
• fistula between the patent esophagus and trachea

Question 10

pseudo glandular stage (details)

Answer 10

• sub-segmental lung buds branch rapidly and dichotomously
• airways develop to the level of the terminal bronchioles by the end of this period
• vessels develop along the generations of airways
• fetus born at this period is unable to survive

Question 11

canicular stage (details)

Answer 11

• lung size increases due to branching of the terminal bronchioles
• by 24 each terminal bronchiole has given rise to respiratory bronchioles
• expansion of capillary network is greatest during this period
• primordial capillary-airspace interface develops
• fetus born can survive with intensive care

Question 12

terminal sac stage (details)

Answer 12

• formation of secondary crests
• ^are ridges of epithelial lined mesenchyme that subdivide into saccules
• intestinal tissue thins
• increase in elastic network around airways
• close contact of type 1 pneumocytes and endothelium establishes the blood air married
• increasing amounts of surfactant increases chances of survival

Question 13

alveolar stage (details)

Answer 13

• interstitial mesenchyme continues to thin
• alveoli form adult shape
• a full compliment of structures will develop by birth
• growth of the lung after birth is due to increase in number of respiratory bronchioles and alveoli
• growth continues until approximately 8-10 year postnatal life

Question 14

at what weeks is pulmonary surfactant produced in measurable amounts

Answer 14

24-28 weeks

Question 15

neonatal respiratory distress syndrome (hyaline membrane disease)

Answer 15

• preterm, male, maternal diabetes
• immaturity of the lungs/ lack of surfactant
• increase in work of breathing result sin a cascade of events that cause hyaline membranes to develop

Question 16

pulmonary hypoplasia

Answer 16

• abnormality with decrease in size and weight of the lung

- most common congenital lesion of the lung

Question 17

3 major factors that may lead to pulmonary hypoplasia

Answer 17

• congenital diaphragmatic hernia
• oligohydramnios
• decreased respiration during fetal period

Question 18

congenital diaphragmatic hernia

Answer 18

• most common malformation of the diaphragm
• peritoneal cavity is continuous with pleural cavity
• result in compression of the lung