III. MIcroanatomy of Avian and Ruminant GI system Flashcards
The avian stomach consists of….
Two organs that function together:
- Proventriculus which contins glands with Oxynticopeptic cells that secrete both HCL and digestive enzymes
- Ventriculus which is extremely motile and serves to mash and grind the ingesta
What do oxyticopeptic cells secrete and what avian organ are they found in?
Oxynticopptic cells secrete HCl nd digestive enzymes and are located within glands of the proventriculus.
T. Mucosa of avian proventriculus
- Epithelium - simple columnar extensive folds (plicae, separated by sulci)
- L. propria - lymphatic tissue
- L. muscularis - split in some species by glands
How is a single papilla formed?
From several plicae, gives star-shaped appearance to lumen.
T. Submucosa of Avian proventriculus
- Compound tubuloalveolar submucosal glands
- Located between layers of the lamina muscularis
- Glandular cells (oxynticopeptic cells) are cuboidal and secrete BOTH Hcl and digestive enzmes
- A central duct drains the secretory product onto the papillae
How many ayers is the T. Muscularis of the avian proventriculus?
Three layers - difficult to discern the individual layers
What is the last tunica of the avian proventiruclus?
Tunica serosa - as in common body cavity
T. Mucosa of avian ventriculus
- Epithelium - columnar
- Mucosal glands - branched tubular with simple cuboidal epithelium (the lining eptiehlial cells are secretory)
- Serete cornified product, cuticle (pellicle) that along with grit, aides in mashing the food, as birds do not have teeth to break down ingested food.
T. Submucosa of avian ventriculus
Nonglandular - unlike proventriculus
T. muscularis of avian ventriculus
- Smooth muscle
- Dense white fibrous c.t.
- thicker than T. muscularis of proventriculus
What is the last tunica of the avian ventriculus?
Tunica serosa - as in common body cavity
What is a common name for avian ventriculus?
Gizzard
Avian small intestine has what kind of nodules?
Lymphatic
The large intestine in avians has…., and function to?
Paired ceca, functions for water resporption and cellulose digestion.
Avian Cloaca
- Excretory (digestive and urinry
- Reproductive
- Immunological function (cloacal bursa)
What do you call the normal glandular ruminant stomach?
Abomasum
Describe the abomasum.
It is the normal glandular ruminant stomach. It is identical to the simple stomch of carnivores and contains the usual glandular ares and cell types present in other species.
What do you call the large non-glandular stomach in ruminants?
Forestomach
Describe the forestomach in ruminants.
- It is a large non-glandular stomach which contains micro-organisms that break down cellulose of plant material.
- Nutrients can then be absorbed across the eptiehlium of the forestomach
Nonglandular ruminant stomach consists of what two parts?
- Forestomach (no glands)
2. Abomasum (glandular)
The forestomach of the ruminant consists of what three parts?
- Rumen
- Reticulum
- Omasum
T. Mucosa of the rumen
- Epithelium - stratified squamous keratinized
- L. propria - extends into papillae, NO GLANDS
- L. muscularis ABSENT - no msucle layers project into rumen papillae
T. Submucosa of the rumen
NO GLANDS
T. Muscularis of the rumen
- Inner circulr layer (smooth muscle)
2. Outer longitudinal layer (smooth muscle)
What is the outer tunica of the rumen?
Tunica serosa
Fermentation end products are absorbed continuously throughout the forestomach, but mostly where?
The rumen
Rumen epithelial cells are adapted for _____.
Absorption
What factors facilitate the removal and uptake of volative fatty acids?
- Rich capilary network
2. Large intercellular spaces
T. Mucosa of the ruminnat reticulum (part of the forestomach)
- Epithelium - stratified squamous epithelium
- L. propria extends into folds - NO GLANDS
- L. muscularis in apex of primary crests. Therefore, the reticular mucosal projections contain a single cross sectional bundle of smooth muscle.
T. submucosa of the reticulum
NO GLANDS
T. muscularis of the reticulum
- Two layers - blique, smooth muscle
What is the outer tunica of the reticulum?
Tunica Serosa
Tunica mucosa of the omasum (part of the forestomach)
- Epithelium - keratinized stratified squamous forms laminae with horny papillae coming off the laminae
- L. Propria vary vascular - NO GLANDS
- L. muscularis thick and extends into laminae
Tunica submucosa of the omasum
NO GLANDS
T. Muscularis of the omasum
- Inner circular - intermediate muscle sheet of lamina
- Since inner circular layer extends into laminae and sandwiches the lamina muscularis layer, there are THREE distinct muscle layers in the omasal laminae (lamina muscularis in cross sectional format, longitudinal section of T. muscularis, and then lamina muscularis in cross sectional format)
- Outer longitudinal
What is the outer tunica of the omasum
Tunica serosa
Omasoabomasal fold
Epithelium changes from stratified squamous keratinized to simple columnar-secretory.
In the rumen, ucosal projections are called?
Papillae
In the reticulum, main mucosal projections are called?
Primary crests
In the omasum, the main mucosal projections are called?
Laminae with horny papillae extending from the laminae
