Salivary Glands
- exocrine glands in mouth
- produce saliva
- formed by invagination of oral epithelium into lamina propria
Functions of saliva
- digestive
- lubrication
- protective
Two Types of Salivary Glands
- Major Salivary Glands
- Minor Salivary Glands
Major Salivary Glands
- large in size
- located some distance from buccal cavity
- excretory ducts are long
ex - Parotid, Mandibular, Sublingual, and Zygomatic
Minor Salivary Glands
- smaller in size
- located close to buccal cavity
- excretory ducts are short
ex- Labial, Lingual, Buccal
Features of Salivary Glands
- All are compound
- All are exocrine
- All are lobulated
- All are merocrine
- Almost all are mixed
- All secrete saliva
Conditioned Reflex Flow of Saliva
Sight or suggestion of food stimulates secretion of saliva
ex - dogs, pigs
Unconditioned Reflex Flow
Presence of food in the mouth stimulates secretion of saliva
ex - ungulates = any animal with hooves
Serous Cells
- usually pyramidal in shape
- round basal nuclei
- well stained RER
- secrete enzymes and other proteins
- small lumen
Mucous cells
- columnar in shape
- compressed basal nuclei
- poorly stained cytoplasm
- secrete mucin
- wider lumen
Myoepithelial Cells
- found inside basal lamina
- contract and expel the secretions out through ducts
Flow of Secretions in Salivary Glands
Adenomere -> intercalated duct -> striated duct -> intra-lobular excretory duct -> inter-lobular excretory duct -> surface epithelium of oral cavity
Parotid Salivary Gland
- exclusively serous in humans and domestic animals
- mixed in puppies…
- compound gland
- secrete alpha-amylase that initiates hydrolysis of carbohydrates
What does a parotid salivary gland resemble? How can it be distinguished?
Looks like pancreas
Parotid Salivary Glands have striated ducts though
Mandibular Salivary Gland
- usually mucous in dogs and cats
- serous in rodents
- mixed in horses, humans, and ruminants
- serous demilunes are prominently seen
- secrete alpha-amylase and lysozyme
- produce 2/3 of all saliva
Sublingual Salivary Gland
- smallest of major glands
- predominantly mucous in ruminants, swine, and rodents
- mixed in small carnivores, humans, and horses
- few serous demilunes are seen
- secrete mucin as main product
esophagus
- muscular tube modified for transport of food to and from the stomach
- flexible and distensible
- voluntary and involuntary movement of food
- 4 layers of GI well represented
What parts of the GI tract have submucosal glands?
esophagus and doudenum
Stomach
- muscular dilation of GI tract
- mechanical and chemical digestion
- Two broad regions: non-glandular and glandular
What parts of the stomach are non-glandular?
- esophageal region
- forestomach in ruminants
What parts of the stomach are glandular?
- cardia
- fundus
- pylorus
What is the Margo plicatus?
raised transitional line from non-glandular to glandular stomach
Ruminant Forestomach
- AKA proventriculus
- 3 compartments: rumen, reticulum, omasum
- all lined with stratified squamous keratinized epithelium
- basically an enormous esophageal stomach
Which compartment of the ruminant stomach is considered the true stomach?
abomasum
