Lecture DIGESTIVE SYSTEM part 2. INTESTINE LIVER PANCREAS. Department of histology, cytology and embryology KhNMU. Small intestine. Functions: digestion – liver, pancreas, enterocytes absorption – enterocytes STRUCTURE: 4 membranes. Intestinal lining:.
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Department of histology, cytology and
1) plicae circularis: mucosa + submucosa
2) villi -consist of:
epithelium, lamina propria, mm
3) crypts: invaginations of epithelium in the lamina propria
simple columnar epithelium: absorptive enterocytes, goblet,
endocrine, Paneth cells and stem cells
fenestrated capillaries and central lacteal
1). Enterocytes = Columnar absorptive cells (a) have microvilli =brush border (bb) for absorption of digested food.
Membrane and luminal digestion
2). Mucus-secreting goblet cells (gc) produce a protective mucus. Lymphocytes and plasma cells (L) are numerous in the lamina propria of the villus.
At the bottom of intestinal glands (crypts) are
3). the granule-containing Paneth cells (p). Lysozyme.
Goblet (g) and absorptive (a) cells.
3. Paneth cells, 4. enteroendocrine cells (CCK, secretin, GIP),
5.undifferentiated cells=stem, at the bottom of crypt
Ducts (d) from Brunner’s glands (Bg) (s) pass through the muscularis mucosa (mm) to empty their alkaline mucus in or between the crypts (c).
The jejunum is like the duodenum & ileum
but has no submucosal glands and Peyer’s patches.
Contains bigger amount of goblet cells
The major distinguishing feature is the aggregated lymphatic nodules (ln) called Peyer’s patchesin the mucosa or submucosa
Plicae circulares (pc) . Unlike the small intestine there are no mucosal villi.
There are straight intestinal glands – crypts (cr) composed mainly of
1. Goblet cells – the most numerous .
2. Columnar absorptive cells
3. Enteroendocrine cells
4. Undifferentiated cells
Liver has specific location – on the way of absorbed material, that is why has very original vasculature and functions
① at its center - central vein
② hepatic plates（cords of cells - hepatocytes）locate radially
③ hepatic sinusoids locate between plates
Central veins (cv) drainto a sublobular vein (sv).
The portal triads (pt) locate at lobule coners.
The bile canaliculus wall is made
up of hepatocytes
Vascular and bile surfaces
c. Golgi complex
Lined by endothelium
Liver had been injected with carbon particles
Kupffer cells containing carbon (red arrows)
A flattened endothelial cell (e)
Space of Disse (d) between it and the hepatocytes
with red gelatin to demonstrate the abundant vasculature.
central vein (cv), the portal triad (pt)
hepatic sinusoids (hs).
Structural features of the acinus:
① Purely serous.
② the presence of centroacinar cells in the center of the acinus
Scattered among exocrine secretory units spherical collections of light-staining cords of endocrine cells
PP, D1, EC,