Histology and Embryology Flashcards
What is the epithelium of the oral cavity, oropharynx, laryngopharynx and buccal surfaces?
Non-keratinised stratified squamous epithelium
What are the only parts of the mouth to be keratinised?
Gingivae (gums) and hard palate
What is the epithelium of the nasal cavity and nasopharynx?
Respiratory epithelium
Describe the epithelium of the anterior 2/3rds of the tongue?
Stratified squamous epithelium- thin on ventral surface and thick with papillae on dorsal surface
Describe the epithelium of the posterior 1/3rd of the tongue?
Smooth stratified epithelium
What is the difference between serosa and adventitia?
If the tissue is embedded in another tissue or pegged down to something else, it is adventitia
What is the epithelium in the oesophagus?
Non-keratinised stratified squamous epithelium
What different types of muscle are found and where in the oesophagus?
Upper 1/3rd- skeletal
Middle 1/3rd- transition
Lower 1/3rd- smooth
What is all the muscle of the oesophagus innervated by?
Vagus nerve
Where are the only places in the GI tract that submucosal glands can be found?
Oesophagus and duodenum
Where is the first sudden change of GI epithelium, what is this change?
At the gastro-oesophageal junction: stratified squamous epithelium to columnar epithelia
What epithelial layer are the gastric pits which make gastric glands in the stomach found?
Muscularis mucosa
What type of cells line the gastric pits and can also be found on the surface?
Surface mucous cells
What does the isthmus of the gastric pits contain?
Stem cells, parietal/oxyntic cells
What does the neck of the gastric pit contain?
Mucous and stem cells
What do chief cells give rise to?
Pepsin
What does the muscularis externa contain only in the stomach?
An extra layer of oblique smooth muscle
What are crypts of Lieberkuhn?
Villi with pits drilling downwards found in the small intestine
Where are the villi on the small intestine found?
On the plicae circularis
What part of the small intestine has the largest villi?
Jejunum
Where are the Peyer’s patches found in the ileum?
Submucosa and sometimes lamina propria
What are enterocytes and what are some of their features?
Main absorptive cell, tall, columnar and with brush border
What do goblet cells produce?
Mucin
What do Paneth cells do?
Involved in defence
What are cells that produce hormones that control secretion and motility?
Enteroendocrine
What do stem cells do?
Replenish the epithelium
What parts of epithelium do the plicae have?
Mucosa and submucosa
What are the relative sizes of the two types of muscle in the ileum? What is the exception to this?
Circular muscle is very thick and longitudinal is very thin- the exception is when the longitudinal muscle is gathered into bands at the teniae coli
What are the principle cell types in the large intestine?
Absorptive and goblet
What is the epithelia of the anal canal?
Stratified squamous- becoming keratinised as it gets nearer the outside world
When is the gut tube formed?
When the embryo folds
What embryological part forms the gut tube?
Lateral aspects of the endoderm meeting
What embryological part forms the body wall?
Mesoderm
What areas of the GI tract are endoderm derived?
Epithelia of mucosa and associated ducts and glands
What areas of the GI tract are visceral mesoderm derived?
Lamina propria, muscularis mucosa and externa, connective tissue
What are ventral mesenteries of the GI tract?
Lesser omentum and falciform ligaments
What are dorsal mesenteries of the GI tract?
Mesoduodenum and mesocolon, superior mesenteric artery
Where do most mesenteries attach?
Dorsal border
What are ventral mesenteries derived from?
Septum transversum
When is the oesophagus distinguishable?
Week 4
When does the circular muscle develop?
Week 5
When does the longitudinal muscle develop?
Week 8
What do the lesser omentum and falciform ligaments form?
Ventral mesentery
Where are parts 1 and 2 of the duodenum derived from?
Caudal part of foregut
Where are parts 3 and 4 of the duodenum derived from?
Cranial part of midgut
What grows into the mesoderm of the septum transversum?
Liver bud
Where do the liver cells and lining of the biliary tree come from?
Endoderm
Is the pancreas always retroperitoneal?
No it is intraperitoneal during development
What is it known as when a mass of pancreatic tissue forms around the duodenum, causing stenosis?
Annular pancreas
Where is the spleen derived from and when does it form?
Mesoderm derived in week 5
When does the spleen develop into a lymphoid organ?
15-18
What connects the midgut to the yolk sac?
Vitelline duct
What is a vitelline fistula?
Open connection from the small intestine to the outside world
When does recanalization of the gut lumen occur?
Week 9
