CVM 712 Lab 10

Intestinal Mucosa

• Simple columnar epithelium

• Goblet cells

  • Increase in number aborally

• Lamina propria – loose connective tissue that holds the epithelium to the muscularis mucosa

• Muscularis mucosa – thin layer of smooth muscle under mucosa

Intestinal Submucosa

Collagenous connective tissue

Intestinal Muscularis externa

• Smooth muscle

  • One layer circular and one layer longitudinal

Intestinal Serosa

Outer layer of connective tissue

Small Intestine

• Villi – only in small intestine

  • Carnivores – long and slender

  • Ruminants – short and thick

• Crypts – at the base of the villi

  • Progenitor cells to replace lost cells

• Brunner’s glands

  • Duodenum submucosa

  • Mucous glands

• Peyer’s patches

  • Ileum and other parts of small intestine

  • Lamina propria

Large intestine

• Mucosa is flat (no villi)

• Crypts are longer

• Horses and pigs have longitudinal bands of smooth muscle and elastic fibers

  • Taeniacoli – bands in the colon

  • Taeniaceci – bands in the cecum

Rectum and Anal Canal 

• Stratified squamous epithelium 

  • Nonkeratinized orally

  • Keratinized aborally

• Carnivores and pigs have tubuloacinaranal glands 

  • Apocrine glands in dogs

  • Apocrine and sebaceous glands in cats 

  • In submucosa and muscularis of anal canal, near anal sphincter 

  • Empty into anal sacs in carnivores 

    • Keratinized stratified squamous epithelium

• Dogs also have circumanal glands or “hepatoid” glands 

  • Sebaceous and nonsebaceous

  • Look similar to hepatocytes 

Liver

• Outer capsule

• Lobes are divided into lobules

  • Hepatocytes in cords

  • Sinusoids

  • Portal tracts or portal triad

    • Portal vein

    • Hepatic artery

    • Bile ductile

    • Lymphatic vessel

  • Central vein

• Bile is secreted by hepatocytes

• Travels through bile canaliculi to bile ducts and stored in gallbladder

  • Except horse, rat, etc.

• Bile ducts have simple cuboidal to simple columnar epithelium

  • Portal triads

  • Some bile ducts have goblet cells

Kupffer Cells (Macrophages)

Gallbladder

• Stores bile

• Simple columnar epithelium

• Cattle and goats have goblet cells too

• Smooth muscle

Pancreas

• Exocrine

  • Glands that secrete enzymes to help with digestion

    • Simple cuboidal

  • Drain to ducts

    • Simple cuboidal

• Endocrine

  • Islets of Langerhans

    • Produce insulin

• Pacinian corpuscles

  • Prominent in cats, sometimes in dogs

What is in the center of this image from the pancreas?

Islet of Langerhans

Pacinian corpuscle

Villi of duodenum

Microvilli of duodenum

What ring-like structure can be found in the submucosa in this picture of the duodenum?

Brunner’s glands (mucus producing)

Small intestine

Villi

Large intestine

Flat

Cecum

No villi, increased goblet cells, longer crypts

Central vein (Liver)

Portal triad (Liver)

Gallbladder

• Much thinner wall compared to the other gastrointestinal tissues

• Storage organ for bile.

• Columnar epithelium in the mucosa, which is thrown into multiple folds, and a very thin muscular layer.