ZOOL 409
Tuesday and Thursday
Lab Week 8
Primary objective:
Examine the digestive tract (several regions) and recognize its various tissue components
and layers.
Slides to examine:
Components to identify:

Slide 32 -- tongue (epithelium, tastebuds,
salivary glands, muscle); compare with Slide 33,
soft palate; Slide 25, tonsil.


Slides 36, 37 (also, in some boxes, Slides 57,
35), esophagus -- (epithelium, layers,
submucosal glands).

Slides 37, 38, 39, 40, 41 -- stomach (epithelium,
pits, mucosal glands, layers).
Layers
o mucosa
 epithelium
 lamina propria
 muscularis mucosae
o submucosa
o muscularis
 inner circular muscular
 outer longitudinal muscle
 Auerbach's plexus (parasympathetic nervous
tissue)
o serosa / adventitia
 connective tissue
 mesothelium

Special cell types
o taste buds on fungiform (or foliate) papillae of
tongue
o absorptive cells (enterocytes) and goblet cells
(mucus-secreting cells) form the epithelium of
small and large intestine.
o Additional cell types will be added to this list
in later labs.

Features of surface shape
o papillae (tongue)
o pits (stomach)
o villi (small intestine)
o crypts (simple tubular "glands" in intestine)
o plicae (folds involving mucosa and
submucosa, small intestine)

Lymphatic features
o lamina propria
o lymph nodules
o tonsils
o Peyer's patches (large clusters of lymph
nodules, in ileum)
o lacteals (lymph capillaries in villi)
The stomach is characterized by a thick, glandular mucosa,
without villi. Cardiac stomach is the upper portion of the
stomach, characterized by short mucous glands in the
mucosa. Pyloric stomach is the lower portion of the
stomach, characterized by longer mucous glands in the
mucosa. The body (fundus) of the stomach is
characterized by gastric glands which may show up on
slide of gastro-esophageal junction [the slide from dog
should show cardiac stomach (immediately adjoining the
esophagus), but apparently in the dog the characteristic
glands of fundic stomach begin very near the esophagus].

Slides 42, 43, 44, 45, 46, 51 -- small intestine
(epithelium, villi, crypts, layers, submucosal
glands in duodenum, lymphoid tissue in ileum).
The regions of the small intestine are very similar. They
all have villi and crypts. They differ (subtly) in the
proportion of goblet cells in the epithelium (increasing
numbers of goblets as one goes down toward the colon)
and in the shape of the villi. More dramatically, the
duodenum (but not other regions) have extensive mucous
glands (Brunner's glands) in the submucosa, and the ileum
has scattered but large masses of lymphoid tissue (Peyer's
patches).

Slides 46, 47, 48, 49, 50 -- colon, appendix
(epithelium, crypts, layers; lymphoid tissue in
appendix). The colon is characterized by a rather thin
mucosa with many straight tubular crypts but no villi.
Goblet cells are extremely numerous. The appendix
resembles the colon, but small and with lots of lymphoid
tissue.
Practice Quiz on back.
Last updated: 8 December 2011 / dgk
Practice Quiz
Do not call for a quiz until you are prepared to
proceed efficiently. Each of the listed structures
should be readily apparent in an appropriate region.
The order of listing should call for minimal stage
movement between one structure and the next.
"Hunting" should seldom be necessary.
□
In addition to the quiz, you are also (as always)
encouraged to seek confirmation for your
recognition of structures on slides from your
reference slide set -- particularly of any features
not included in these quizzes.
□
□
Layers of tongue:
____Mucosa
____ Stratified squamous epithelium
____ Taste bud
____ Lamina propria
____Striated muscle
Layers of esophagus:
____Mucosa
____ Stratified squamous epithelium
____ Muscularis mucosae
____Submucosa
____Muscularis externa
____ Smooth muscle
____ Skeletal muscle (scattered fibers)
□
□
Layers of small intestine:
____Mucosa
____ Lamina propria of villus
____ Lamina propria between crypts
____ Mitotic figure in crypt epithelium
____ Lymphoid tissue
____ Muscularis mucosae
____Submucosa
____ Artery, vein
____Muscularis externa
____ Inner circular muscle
____ Outer longitudinal muscle
____Auerbach's plexus
Layers of colon:
____Mucosa
____ Crypts cut lengthwise
____ Crypts cut in cross section
____ Lamina propria between crypts
____ Muscularis mucosae
____Submucosa
____Muscularis externa
Layers of appendix:
____Mucosa with crypts
____ Lymphoid tissue
____Submucosa
____Muscularis externa
____ Inner circular muscle
____ Outer longitudinal muscle
Last updated: 2 March 2011 / dgk
□
Layers of stomach:
____Mucosa
____ Simple columnar epithelium
____ Lamina propria
____ Muscularis mucosae
____Submucosa
____Auerbach's plexus