GIT-3 RUMINANT

GIT-3 RUMINANT

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Objectives1. You should appreciate how the forestomach

markedly differs in its histological structure from the abomasum - the glandular stomach.

2. You should appreciate the similarities and differences between the histological structures of rumen, reticulum and omasum.

3. You should appreciate the similarity of the ruminant glandular stomach with a non-ruminant animal like for example a dog.

Cadaver in right lateral recumbency.Left abdominal wall reflected cranially over ribcage.Rumen & intestines in situ. Note extent of rumen covered by ribcage.

1- Abdomen - Sheep

Identify: dorsal & ventral sacs of rumen, caudodorsal blind sac, caudoventral blind sac, caudal sulcus, dorsal coronary sulcus, ventral coronary sulcus, ansa spiralis of ascending colon

2- Abdomen - Sheep

Sternum transected along midline,ribs reflected craniolaterally.Diaphragm partially reflected from costochondral arch to expose left lung, thymus, & heart within pericardium.

Identify: reticulum, rumen, abomasum, spleen, myotendinous junction of diaphragm, left lung, pericardium, thymus.

Note proximity of reticulum to diaphragm and pericardium - why is this of clinical significance?

Identify: abomasum, reticulum, diaphragm, spleen, left ventricle, right ventricle, left interventicular paraconal sulcus, apex of heart, thymus.

3 & 4 - Abdomen - Sheep

Diaphragm partially removed (cut edge apparent).Pars caudalis of cranial lobe of left lung reflected dorsally. Pericardium partially removed to expose heart.

• Cadaver in right lateral recumbency. Rumen reflected cranially to expose small & large intestine..• Identify: Jejenum, ansa spiralis of ascending colon (ansa proximalis, centripetal gyri, flexura centralis, centrifugal gyri).• Also visible: Greater omentum attached to rumen, left kidney.

Abdomen - Sheep

Cadaver in left lateral recumbency. Right abdominal wall reflected dorsally & ribcage removed. Left lobe of liver in situ, right liver lobe reflected cranially to expose visceral surface of left & right lobes, caudate process, gall bladder, bile duct, portal vein, & omasum.

Identify: Abomasum (greater & lesser curvatures), lesser omentum, sigmoid loop of duodenum, descending duodenum, ascending duodenum, pancreas, rumen & greater omentum, jejunum, caecum & ansa proximalis of ascending colon.

Also visible: right kidney (note relationship to liver), right lung. Yellow staining of greater omentum is post-mortem artefact resulting from leakage of bile through gall bladder wall.

Abdomen - Sheep

SLIDE 35 RumenIn the ruminant the forestomach consists of the rumen, the reticulum and the omasum. Shown below: a low magnification view of the rumen.

1.0 mm

SLIDE 35 RumenIn the ruminant the forestomach consists of the rumen, the reticulum and the omasum. Shown below: a low magnification view of the rumen.

Area of rumen selected.

1.0 mm

SLIDE 35 Rumen Identify: papillae mucosal layer (epithelium and lamina propria) submucosa tunica muscularis serosa

1.0 mm

SLIDE 35 Rumen Identify: papillae mucosal layer (epithelium and lamina propria) submucosa tunica muscularis serosa

1.0 mm

mucosa submucosa (extends into the large papillae)

tunica muscularis

serosa

papilla

SLIDE 35 RumenThe tunica muscularis comprises a thick layer in the rumen (smooth muscle).An inner circular layer and an outer longitudinal layer are clearly defined.

250 µm

SLIDE 35 RumenThe tunica muscularis comprises a thick layer in the rumen (smooth muscle).An inner circular layer and an outer longitudinal layer are clearly defined.

250 µm

submucosa

inner layer

outer layer

tunica muscularis

serosa

SLIDE 35 RumenCan you see the boundary between mucosal and submucosal layers?

250 µm100 µm

SLIDE 35 RumenCan you see the boundary between mucosal and submucosal layers?No, because of the absence of the lamina muscularis.

250 µm100 µmE : epithelium (mucosa)L : lamina propria (mucosa)S : submucosa (with blood vessels)T : tunica muscularis

E

T

S

L

SLIDE 35 Rumen

250 µm

Rumen - Sheep

Rumen wall incised and reflected cranially to show papillated, non-glandular mucosa & rumenal pillar. Serosal surface of rumen and spleen also apparent.

Compare mucosa with that of reticulum, omasum & abomasum elsewhere in series.

Note consistency of rumenal ingesta and compare with that of reticulum, omasum& abomasum elsehere in series.

What type of epithelium covers the surface?

SLIDE 35 Rumen

250 µm

What type of epithelium covers the surface?Keratinised stratified squamous epithelium.

epithelium keratinised stratified squamous

submucosa

lamina propria

tunica muscularis

keratinised surface

SLIDE 35 RumenWhy is it the most appropriate covering here?

50 µm

SLIDE 35 RumenWhy is it the most appropriate covering here?1. Because it breaks down the roughage in the food.2. Protects the lining from damage.

50 µm

stratified squamousepithelium

keratinised surface layer

lamina propria

SLIDE 35 RumenWould you expect to see any glands here?

100 µm

SLIDE 35 RumenWould you expect to see any glands here?No.

100 µm

epithelium

lamina propria

submucosa

blood vessel

lumen

SLIDE 36 ReticulumIdentify: papillae mucosal layer (epithelium, lamina propria, lamina muscularis) submucosa tunica muscularis serosa

2.0 mm

SLIDE 36 ReticulumIdentify: papillae mucosal layer (epithelium, lamina propria, lamina muscularis) submucosa tunica muscularis serosa

2.0 mm serosa(indistinct)

tunica muscularis

submucosamucosa

papillae (primary reticular folds)

SLIDE 36 ReticulumIdentify: papillae mucosal layer (epithelium, lamina propria, lamina muscularis) submucosa tunica muscularis

1.0 mm

Reticulum - Sheep

▪ Reticulum in situ. Reticulum wall incised and reflected cranially to expose mucosa.

▪ Note consistency of reticulum ingesta

▪ Also visible: diaphragm (cut edge), left lung, heart, thymus, liver.

SLIDE 36 ReticulumIdentify: papillae mucosal layer (epithelium, lamina propria, lamina muscularis) submucosa tunica muscularis

1.0 mm

papilla

conical papillae

inner layer of tunica muscularis

epithelium

submucosa with blood vessels extending into papilla

lamina propria

lamina muscularis

connective tissue band between lamina propria and submucosa

lamina propria

SLIDE 36 ReticulumIn this area of primary papilla secondary papillae. identify: epithelium, lamina propria and lamina muscularis, part of submucosa extending into papilla.

0.5 mm

SLIDE 36 ReticulumIn this area of primary papilla secondary papillae. identify: epithelium, lamina propria and lamina muscularis, part of submucosa extending into papilla.

0.5 mm

epithelium

lamina propria

LM : lamina muscularis

S : submucosa

S

LM

secondary papilla

band of connective tissue

SLIDE 36 ReticulumHow would you describe the lamina muscularis here?

100 µm0.5 mm

SLIDE 36 ReticulumHow would you describe the lamina muscularis here?Seen as blocks of (smooth) muscle; isolated in both short and tall folds.

100 µm0.5 mm


epithelium

lamina propria

LM

LM

SLIDE 36 ReticulumThe tunica muscularis consists of two thick layers of smooth muscle.With inner circular and outer longitudinal layers.The appearance of muscle tissue on slides depends on how the sample has been cut for histology (longitudinal, transverse or oblique sections).

1.0 mm

SLIDE 36 ReticulumThe tunica muscularis consists of two thick layers of smooth muscle.With inner circular and outer longitudinal layers.The appearance of muscle tissue on slides depends on how the sample has been cut for histology (longitudinal, transverse or oblique sections).

1.0 mm

mucosa

S : submucosa with blood vessels

inner layer of tunica muscularis

outer layer of tunica muscularis

thin layer of serosa

S

SLIDE 36 ReticulumWhat are secondary papillae?

250 µm

1.0 mm

SLIDE 36 Reticulum

250 µm

1.0 mm

primary papilla or lamina secondary papillae

What are secondary papillae?They are conical papillae projecting from the mucosa on the crests of folds and from the compartments between primary papillae.

SLIDE 36 ReticulumHow is the mucosal layer divided into compartments here?

250 µm

1.0 mm

SLIDE 36 ReticulumHow is the mucosal layer divided into compartments here?It forms a honeycomb of intersecting short and tall folds.

250 µm

1.0 mm

LP : lamina propriaS : submucosaT : tunica muscularisB : blood vessel

T

T

LP

B

B

fold (primary papilla)

S

S

SLIDE 36 ReticulumWhat type of epithelial lining is present?

50 µm

SLIDE 36 ReticulumWhat type of epithelial lining is present?Keratinised stratified squamous epithelium.

50 µm

lamina muscularis lamina propria stratified squamous epithelium

keratinised layer

SLIDE 37 OmasumIdentify: laminae mucosal layer (epithelium, lamina propria, lamina muscularis) submucosa tunica muscularis serosa

2.0 mm

SLIDE 37 OmasumIdentify: laminae mucosal layer (epithelium, lamina propria, lamina muscularis) submucosa tunica muscularis serosa

2.0 mm

laminae (extend like pages of a book)

serosa tunica muscularis

submucosa arrowed

mucosal layer (see higher magnifications)

SLIDE 37 Omasum

0.5 mm

Identify : laminae. mucosal layers 1. epithelium 2. lamina propria 3. lamina muscularis extension of tunica muscularis

Omasum - Sheep

▪ Cadaver in right lateral recumbency. Omasum in situ. Wall incised to expose mucosa & omasal laminae.

▪ Note consistency of omasal ingesta.

▪ Also partially visible: Liver (reflected caudally), abomasum & greater omemtum.

SLIDE 37 Omasum

0.5 mm

Identify : laminae. mucosal layers 1. epithelium 2. lamina propria 3. lamina muscularis extension of tunica muscularis

laminae

epithelium

LM : lamina muscularisLP : lamina propria

part of tunica muscularis

LMLM

LP

LP

SLIDE 37 OmasumHow many layers of smooth muscle do you see within each lamina?

250 µm

SLIDE 37 OmasumHow many layers of smooth muscle do you see within each lamina?Three.

250 µm

smooth muscle layers 1-2-3.

epithelium

LP : lamina propria

LP

LP

1 23

SLIDE 37 OmasumTo which muscle layers do they belong?

100 µm

SLIDE 37 Omasum

100 µm

To which muscle layers do they belong?Outer layers are the lamina muscularis.The inner layer is the tunica muscularis.

LM : lamina muscularisTM : tunica muscularisLP : lamina propria

epitheliumLM LMTM

LP

LP

SLIDE 37 Omasum

Outer layers are the lamina muscularis.The inner layer extends from the tunica muscularis.

250 µm

1.0 mm

SLIDE 37 Omasum

Outer layers are the lamina muscularis.The inner layer extends from the tunica muscularis.

250 µm

1.0 mmLM : lamina muscularisTM : tunica muscularisLP : lamina propria

TM

TM

LMLM

LP

LP

epithelium

SLIDE 37 OmasumWhat is the epithelium type?

100 µm

SLIDE 37 OmasumWhat is the epithelium type?Keratinised stratified squamous epithelium.

100 µm

lumen

E : epitheliumLM : lamina muscularisLP : lamina propria TM : tunica muscularis

E

LPLM TM

SLIDE 37 OmasumKeratinised stratified squamous epithelium of omasum.

50 µm

SLIDE 37 OmasumKeratinised stratified squamous epithelium of omasum.

50 µmkeratinised surface

lamina propria

lamina muscularis

keratinised stratifiedsquamous epithelium

• Cadaver in left lateral recumbency.• Right abdominal wall reflected dorsally & ribcage removed.• Duodenum pulled dorsally with forceps to highlight pylorus.

• Identify: Abomasum & greater omentum, rumen, left & right lobes of liver, gall bladder, duodenum, pancreas, jejunum.• Also visible: right kidney (note relationship to left lobe & caudate process of liver), right lung, apex of heart, remains of diaphragm

Abdomen - Sheep

SLIDE 38 Abomasum (glandular stomach)

2.0 mm

Abomasum - Sheep

▪ Abomasal wall incised and reflected to expose mucosa▪ Rumen & omasum also opened ▪ Compare mucosae to that of abomasum▪ Compare texture of ingesta in each compartment

SLIDE 38 Abomasum (glandular stomach)Select an area of the abomasum.

2.0 mm

SLIDE 38 Abomasum (glandular stomach)Identify the main regions in the wall of the abomasum.

1.0 mm

SLIDE 38 Abomasum (glandular stomach)Identify the main regions in the wall of the abomasum.

1.0 mm

mucosa : epithelium,lamina propria with glands and lamina muscularis submucosa : extends into ‘folds’

tunica muscularis

serosa

SLIDE 38 Abomasum (glandular stomach)Submucosa:The submucosa consists of loose connective tissue with unilocular adipocytes and many blood vessels.

100 µm250 µm

SLIDE 38 Abomasum (glandular stomach)Submucosa:The submucosa consists of loose connective tissue with unilocular adipocytes and many blood vessels.

100 µm250 µmA : arterioleV : venule

LM : lamina muscularisTM : tunica muscularis

V

A

TM

LM

adipocytes

submucosa

SLIDE 38 Abomasum (glandular stomach)What is the epithelium type here?

50 µm

SLIDE 38 Abomasum (glandular stomach)What is the epithelium type here?Simple columnar, secretory epithelium.

50 µm

lumen

columnar epithelium

mucosal glands

G : gastric pitsLP : lamina propria

LP

LP

G

G


50 µm

lumen

columnar epithelium

mucosal glands


LP

LP

G

G

Why is this sudden change?


50 µm

lumen

columnar epithelium

mucosal glands


LP

LP

G

G

Why is this sudden change?Requirement for digestion in this region.

SLIDE 38 Abomasum (glandular stomach)Which tissue layers here differ from the forestomach the most and why?

250 µm


250 µm

Which tissue layers here differ from the forestomach the most and why?The mucosal layer is most altered because of the requirement for digestion whereas it was mainly mechanical breakdown in the forestomach.

E : epitheliumLP : lamina propria with tubular mucosal glandsLM : lamina muscularisS : submucosa TM : tunica muscularis

E

LM

LP

S

TM

SLIDE 38 Abomasum (glandular stomach)Glandular area of mucosa (lamina propria) with underlying smooth muscle of the lamina muscularis.Deeper to this is the submucosa in which some blood vessels are visible.

50 µm

SLIDE 38 Abomasum (glandular stomach)Glandular area of mucosa (lamina propria) with underlying smooth muscle of the lamina muscularis.Deeper to this is the submucosa in which some blood vessels are visible.

50 µm

lamina muscularis

blood vessel in submucosa

glands in lamina propria


2.0 mm

Compare this section with that of the pyloric region of the canine stomach.

SLIDE 33 Pyloric region of glandular stomach (dog)Identify the main layers of the stomach.

1.0 mm

SLIDE 33 Pyloric region of glandular stomach (dog)Identify the main layers of the stomach.

1.0 mm

Identify the main layers of the stomach.Mucosa, submucosa, tunica muscularis (very thick layer) and serosa.Due to the large size of this specimen the 4th layer of serosa is not shown.

tunica muscularis submucosa mucosa

lumen

split in tissue(artefact)

SLIDE 33 Pyloric region of glandular stomach (dog)Identify : deep gastric pits coiled glands in lamina propria opening into gastric pits lamina muscularis

250 µm


LM

gastric pits

C : coiled glands

C

Lectures. Dr Tej Dhoot.Second Year Histology. 019. GIT-3, RUMINANT STOMACH. J.Bredl. 05-08-04. Gross Anatomy Correlates. Dr S.Frean. Slides and Stains. Tanya Hopcroft. Compressed and updated version. 2006/7.

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GIT-3 RUMINANT