1. Structural characteristic of small intestine
4. small intestinal glands located in the lamina
propria.

2. Model H.E. staining villus Longitudinal section of villus and glands A
Core of villus
epithelium
villus
Smooth m.f.
gland A
gland L V
Longitudinal section of
villus and glands

4. Structures increasing surface area
of small intestine
*Plica :
a fold of mucosa and submucosa in the lumen of digestive tract.
*intestinal villus :
the projection of mucosa of small intestine.
*microvillus:
the minute projection of cell membrane.

5. plicae
microvilli
villus

6. microvilli
plica Villus
epithelium

8. Structure of Intestinal Villus:
*small finger projection of the mucosa, found only
in the small intestine;
*varying in the form and height in different region.
1. being covered by s. c. epith.
2. having a core of lamina propria
with capillary network,
central lacteal,
a few smooth muscle f. and
some lymphoid tissue.

9. capillary network
central lacteal
smooth muscle f.
lymphoid tissue

10. Structure of Intestinal Villi:
Simple Columnar Epith.
*cellular types in simple columnar epith. of
intestinal villi are as follow:
* Absorptive cell
Goblet cell
Endocrine cell

11. Absorptive cell * a tall columnar cell with ovoid nucleus
located toward the base.
* striated border(LM) formed by closely
packed, parallel microvilli (EM).
tight junction near the apex between adjacent cells.
* function as absorption of sugar, amino acid and lipid.
* involving in secretion of IgA and producing
enterokinase.(肠致活酶)

12. striated border

13. intestinal villi (SEM)

14. SEM Absorptive cell 微绒毛 LM(model) EM Microvilli Striated border
Tight Junction
SEM
微绒毛
LM(model) EM

15. Model of villi and gland
H.E. staining
Core of villus
epithelium
villus
Smooth m.f.
gland A
gland L V
Longitudinal section of
villus and glands
Model of
villi and gland

16. Small intestine gland *infolding the epithelium to the lamina propria
at the base of villus
*cellular components are as
same as that in the villous
epith., except two types of cells:
Goblet c.
Absorptive c.
Paneth c.
Stem c.
Endocrine c.

17. Paneth cell * found only in the base of the gland.
* pyramidal shape with a broad
base and a narrow apex.
* having all features of protein-
secreting cells.
* acidophilic granules in the apical
cytoplasm (LM).
* secreting defensin, lysozyme
which involved in the control of infection.
Paneth c.

18. Paneth cell
Section (HE)

19. Paneth cell
(EM)
Paneth cell
(LM)

20. Regional difference in the small intestine
duodenum
jejunum
ileum
Villi shape
leaf-like
finger-like
becoming smaller ++
Goblet C. +
+++
scattered L.C. Same as in
solitary L.N. duodenum
Lymphatic
tissue
aggregated L.N.
Glands in
submucosa
Present none none

22. ileum

23. Large intestine
colon
cecum
rectum
appendix
anal canal

24. Large intestine * primary function is reabsorption of water and salt.
* three main sections:
cecum including the appendix
colon
rectum with the anal canal
* primary function is reabsorption of water
and salt.
* secreted mucus acts as a lubricant during
transport of the intestinal contents .

25. Longitudinal section of colon
Structural characteristic of cecum, colon & rectum
*absence of villi & plicae circulares.
*the glands are longer, and straighter.
*surface and gland epith. with numerous goblet c.
Longitudinal section of colon

26. *absence of villi & plicae circulares.
Structural characteristic of cecum, colon & rectum
*absence of villi & plicae circulares.

27. Structural characteristic of cecum, colon & rectum
*the glands are longer, and straighter.
*surface and gland epith. with numerous goblet c.

28. Colon

29. Appendix

30. Structural characteristic of appendix
* small lumen with usually irregular outline.
* surface epith. with few goblet cells.
* rare intestinal glands.
* numerous lymphoid tisues located in
the lamina propria and the submucosa.
* muscularis mucosa usually incomplete.
* thin muscularis.
* serosa.

31. Appendix(transverse section)
L.N.
L.N.
Appendix(transverse section)

33. Mucous neck cell *located in the neck of the gland in small groups;
* flatten nucleus located in the base of cell;
* mucin granules lie in the
supranuclear position;
* secreting acid mucus.

34. Stem cell Endocrine cells *a group of undifferentiated cells located
in the neck region of the gland;
*differentiating into surface mucous cells, chief cells and parietal cells;
Endocrine cells
*ECL cell：secreting histanine stimulated the acid
production.
*D cell: secreting somatostatin inhibited secretion
of parietal cells and other endocrine cells.

35. Regional difference in the small intestine
duodenum
jejunum
ileum
Villi shape
leaf-like
finger-like
becoming smaller ++
Goblet C. +
+++
scattered L.C. Same as in
solitary L.N. duodenum
Lymphatic
tissue
aggregated L.N.
Glands in
submucosa
Present none none

36. Goblet cell *scatted between the absorptive cells.
*increasing from the duodenum to the terminal ileum.
*secreting mucus formed a protective film and
functioned as lubrication.