Embryology & Histology

Question 1

What derm layer gives rise to the gut tube?

Answer 1

Endoderm

Question 2

What is special about the pancreas in terms of embryology?

Answer 2

It is derived from two separate structures

Question 3

Describe the cells lining the oral cavity, oropharynx and laryngopharynx.

Answer 3

Stratified squamous epithelum which is generally not keratinized

Question 4

What are the four types of papillae found on the tongue?

Answer 4

Fungiform
Circumvallate
Foliate
Filiform

Question 5

How does the histology change at the gastro-oesophageal junction?

Answer 5

Abrupt transition from stratified squamous epithelium of oesophagus to the columnar epithelium of the cardia of the stomach

Question 6

What are gastric pits?

Answer 6

Hole in the surface of the inner layer of the stomach, made up of 1-7 gastric glands
Gastric pits are lined by surface mucus cells

Question 7

How does the mucosa differ in the cardia vs body vs pylorus of the stomach?

Answer 7

Cardia - deep gastric pits that branch into loosely packed, tortuous glands.
Body - shallow gastric pits with long straight gastric glands.
Pylorus - deep gastric pits with branched, coiled gastric glands at a higher density than in the cardia.

Question 8

What is significant about the muscularis externa of the stomach?

Answer 8

The muscularis externa of the stomach is unusual in that in areas it contains an additional layer. This layer is oblique to the usual circular and longitudinal muscle layers and is located internal to the circular layer. This layer aids the churning action of the stomach.

Question 9

Compare histologically the regions of the small intestine

Answer 9

Duodenum: Contains Brunner’s glands in the submucosa.
Jejunum: Tallest villi, located on permanent circular folds of the mucosa and submucosa, the plicae circularis.
Ileum: Characterized by aggregations of lymphoid follicles called Peyer’s patches found in the submucosa and often extending into the lamina propria, also LOTS of lymphoid tissue