Micro of Esophagus, Stomach, SI and LI Flashcards
Describe the eptihelium of the Tunica Mucosa in the different tissues of the GI system
Variable in the esophagus - it can be keratinized or non-keratinized stratified squamous epithelium.
The glandular stomach regions are lined by simple columnar epithelium WITHOUT goblet cells
Describe the lamina muscularis of the Tunica Mucosa in different tissues of the GI system
- +/- in esophagus of different species
- different regions of the glandular stomach
- Absent in rumen of ruminant animals
- When present, ALWAYS smooth muscle
- When the lamina muscularis is absent, the lamina propria and submucosa blend insensibly together
Describe the Tunica Submucosa in different tissues of the GI system
- In some species, esophagus will contain submucosal glands
- Glandular stomach regions in mammals DO NOT contain submucosal glands
- Instead, glands are located in tunica mucosa, but they don’t necessarily produce mucous secretion.
- Proventriculus or glandular stomach in birds contains submucosal glands
Describe the Tuncia Muscularis in different tissues of the GI system
- Inner circular layer
- Outer longitudinal layer
- In the esophagus, tunica muscularis can be variable with all skeletal muscle, all smooth muscle, or a combination between the two
- Tunica muscularis of the stomach is ALWAYS smooth muscle in mammals and birds
Describe the Tunica Serosa/Adventitia in different tissues of the GI system
- Last layer will be a tunica adventitia in portions of the organ outside of a body cavity (e.g., cervical esophagus)
- When the esophagus connects to the stomach in the badominal cavity, the last layer will be considered tunica serosa, as a mesothelial lining will be present
- All sections of stomach have tunica serosa
Key features of mammalian esophagus - canine
- Non-keratinized stratified squamous eptiehlial lining
- Lamina muscularis
- Submucosal glands
- Tunica muscularis = skeletal muscle
Key features of mammalian esophagus - ruminant
- Keratinized stratified squamous epithelial lining
- Lamina muscularis
- No submucosal glands
- Tunica muscularis = skeletal muscle
Key features of mammalian esophagus - porcine
- Keratinized stratified squamous epithelial lining
- Lamina muscularis can be scant (cranially) to thick (caudally)
- Submucosal glands only in cranial region
- Tunica muscularis = skeletal muscle cranially; mixture of skeletal and smooth muscle caudally
Key features of avian esophagus
- Keratinized stratified squamous epithelial lining
- Mucosal glands
- Lamina muscularis
- No submucosal glands
- Tunica muscularis = smooth muscle
Key features of avian crop
- Keratinized stratified squamous epithelial lining
- No mucosal glands
- Lamina muscularis
- No submucosal glands
- Tunica muscularis = smooth muscle
What organs may be included in the esophageal-stomach junction?
Depending on the species, a section through the esophageal-stomach junction may contain the esophagus and cardiac gland stomach (such as the pig) or even the esophagus, cardiac gland stomach, AND fundic gland stomach.
Tunica muscularis in esophagueal-stomach junction
Striated muscle (in case of dogs and ruminants) to smooth muscle
How do you distinguish esophageal-stomach junction from a recto-anal canal junction?
The absence of goblet cells in the stomach distinguishes the esophageal-stomach junction from the recto-anal canal junction.
What class of mammals have the best developed nonglandular stomach?
Ruminant
What species have simple glandular stomach and what are its characteristics?
It is present in all species.
Characterized by rugae (macroscopic) and gastric pits (microscopic).
Where are gastric pits and gastric glands present in the stomach?
Present in all regions of the glandular stomach.
The length of the gastric pits and gastric glands is one method to distinguish the cardiac stomach from the pyloric stomach.
Microanatomy of Tunica mucosa of the glandular stomach
- Simple columnar epithelium - secretory (mucous)
- L. propria-gastric glands
- L. muscularis - three layers of smooth muscle
Microanatomy of tunica submucosa of the glandular stomach
Glands only at junction with duodenum
Microanatomy of Tunica muscularis of glandular stomach
All smooth muscle:
- Inner - oblique
- Middle - circular
- Outer - longitudinal
What is the outer must layer of the glandular stomach?
Tunica SEROSA
What are the four regions of the stomach?
- Non-glandular
- Cardiac region
- Fundic region
- Pyloric region
Characteristics of cardiac gland region:
- Branched, coiled tubular glands
- Mucous cells with few endocrine cells
- May see in combination with esophagus (non-glandular stomach)
- Short gastric pits, deep gastric glands
- Nuclei of mucous glands round and tend to be centrally located.