Devo Lect 17 - Endoderm

Question 2

Main tissues from endoderm

Answer 2

Digestive tube (gut, liver, gall bladder, pancreas), respiratory tube (trachea, bronchi, lungs)

Question 3

Pharyngeal Arches

Answer 3

Form early (stage 14, 30 days), 4 pairs; found in all vertebrates

Question 4

Structures from pharyngeal ouches

Answer 4

Inside the arches, lined with endoderm cells, become 1: auditory tube and tympanic cavity; 2: tonsils; 3: Parathyroid and thymus; 4. Thyroid and parathyroid.

Question 5

Cartilages formed from pharyngeal pouches

Answer 5

1. Meckel’s cartilage (jaw), malleus and incus; 2. Stapes, styloid process; 3. Hyoid bone; 4. Thyroid and cricoid cartilage and tracheal rings

Question 6

Changes in digestive tube

Answer 6

Cells become specialized - gastric glands, intestinal cells (microvilli); due to endoderm-mesoderm interactions

Question 7

Liver development

Answer 7

Hepatic diverticulum buds from the foregut as foregut develops; mesenchyme cells induce endoderm cells to proliferate;

Question 8

Stage 23

Answer 8

About two months; end of embryogenesis, all organs are formed. After this it is called a fetus

Question 9

Respiratory tube development

Answer 9

induction from mesenchyme cells around it; buds from the pharynx, then branches; laryngotracheal endoderm - lining of trachea, bronchi, alveoli - different types of cells (due to GFs); lungs one of last organs to fully develop

Question 10

Fetal respiration

Answer 10

Diaphragm becomes functional in last trimester, begins to contract, fetus inhales small amounts of amniotic fluid; helps passages of lungs to expand and expand, not collapse;

Question 11

Premature babies and respiration

Answer 11

Lungs contain water early on, which will cause the lungs to collapse; development of surfactant in the lungs comes around 6 months; surfactant is made of lipids which disperse the water; if born before then they baby might have trouble breathing