Ppt of histology

2. Fig. 18.4:
Histology
of
duodenu
m. Low
magnificat
ion
(practice
figure)

3. Flowchart 18.1: Histology of
duodenum

4. Fig. 18.6: Histology of jejunum (typical
features of small intestine). Low

5. Flowchart 18.2: Histology of jejunum

6. Fig. 18.8:
Histology of
ileum (practice
figure).

7. ILEUM
 Ileum is the distal part of the small intestine.
 It opens in cecum at ileocecal junction.
 Length: 3.5 m.
 The wall of the ileum has four layers: mucosa, submucosa, muscularis externa and
serosa (Figure 18.6).
• Mucosa
• Ileum shows:
 Plicae circularis
 Villi
 Lining epithelium: Simple columnar epithelium with striated border (microvilli) and
goblet cells.
 Lamina propria: Lamina propria contains intestinal glands and Payer’s patches. Neet,
Identification feature
 Muscularis mucosa is thin and even absent at the site of large Payer’s patches.

8. ILEUM
Submucosa, Muscularis externa, Serosa
 Few authors mentioned that payer’s patches
are present in submucosa. But histologically
Payer’s patches are present in lamina propria
and basically may extend into submucosa. Neet

9. Box 18.1: Peyer’s Patches
Q. Write a short note on Payer’s patches.
 Peyer’s patches are organized lymphatic nodules in the lamina propria
of the terminal part of the ileum.
 These are elongated thickening of intestinal mucosa (few centimeters in
length).
 Number: about 100 Payer’s patches are present in ileum.
 Payer’s patches are aggregation of lymphatic follicles.
 At many places, Payer’s patches cross muscularis mucosae extend into
submucosa.
 Payer’s patches form apart of gut-associated lymphatic tissue (GALT).
 Payer’s patches are found in antimesenteric border of ileum.
 M-cell: These are columnar epithelial cells that overlie Payer’s patches.
These cells have recesses to accommodate lymphocytes and
macrophages. M-cell presents bacterial antigens to immune cells.
 Function: Payer’s patches help to maintain normal bacterial intestinal
flora and prevents infections.