Liver / histology / discussion / viva / oral / questions

1. What type of gland is liver?
• Liver is both endocrine and exocrine gland
2. What are the functions of liver?
• Produces and secretes many circulating plasma proteins
• Plays an important role in uptake, storage and distribution of nutrients and vitamins from bloodstream
• Maintains blood glucose level
• Regulates circulating levels of very low density lipoproteins
• Degrades or conjugates numerous toxic substances and drugs
• Secretes bile containing salts, phospholipids, and cholesterol
3. What is Glisson’s capsule?
• It is the connective tissue sheath covering the liver. It is nothing but serous peritoneum covering liver.
4. Name the 3 functional units of liver
• Liver lobule or hepatic lobule or classic lobule
• Portal lobule
• Portal acinus or liver acinus
5. Describe hepatic lobule / What is hepatic lobule
• It is hexagonal unit where plates of liver cells or hepatocytes and sinusoids radiate towards periphery from central vein. At periphery it is bounded by portal triads.
6. What are portal triads?
• Portal triads are spaces containing connective tissue with branches of hepatic artery, hepatic portal vein and bile duct.
7. What is space of Mall?
• Space of Mall is the space present between the portal triad and radiating hepatocytes.
8. Describe portal lobule
• It is triangular area present between three central veins closest to one portal triad which includes three adjacent hepatic lobules. The bile secreted from this area drains into the bile duct in portal triad present in center of three adjacent hepatic lobules
9. Describe portal acinus or liver acinus
• It is diamond shaped area which includes two adjacent hepatic lobules close to axis defined by terminal branches of portal triad. The branch of hepatic artery supplies the two adjacent hepatic lobules. The part close to the axis receives more oxygenated blood compared to regions near the central veins which gets the least.
10. What are hepatic sinusoids?
• They are tortuous, dilated blood channels lined by discontinuous layer of fenestrated endothelial cells and phagocytic Kupffer cells. The exchange of materials occurs here between hepatocytes and blood.
11. What is space of Disse?
• The space present between the hepatocytes and the endothelial cells of sinusoids is called space of Disse.
12. What is the direction of blood flow in liver?
• Portal vein and hepatic artery à sinusoids à central vein à venules à veins à hepatic vein à inferior vena cava
13. What is direction of bile flow?
• Hepatocytes à bile canaliculi à bile ducts àlarge hepatic ducts
14. Name the fibers which form the supporting network in liver
• Reticular fibers line the sinusoids, support the endothelial cells and form dense network of reticular fibers in the wall of central vein
15. Where does the blood from hepatic artery and portal vein mix?
• Hepatic sinusoids
16. What is function of Kupffer cells?
• Kupffer cells are a type of macrophages which is phagocytic in nature lining the sinusoids.
17. What are the cells lining the sinusoids?
• Squamous cells
• Kupffer cells
18. What is the difference between space of Disse and space of Mall?
• Space of Disse is the space between the endothelial cells and hepatic cells
• Space of Mall is present between portal triad and hepatic cells
19. What is the difference between hepatic and portal lobule?
• Hepatic lobule: hexagonal unit with central vein and radiating hepatic laminae surrounded by portal triads at periphery
• Portal lobule: is the area where bile is drained by bile duct in the protal triad which is present between three central veins of adjacent hepatic lobules

Appendix / histology / discussion / viva / oral / questions

1.  What are the four main layers of appendix?
• From within (lumen) outwards
• Mucosa (mucous membrane)
• Submucosa
• Muscularis externa
• Serosa or adventitia
2. What are the layers of mucosa?
• From lumen outwards
• Epithelial lining
• Lamina propria
• Muscularis mucosae
3. What is the epithelial lining in appendix?
• Simple columnar epithelium and numerous goblet cells
4. What are the components of lamina propria?
• Loose connective tissue
• Blood vessels
• Lymphatics
• Nerves
• Few Crypts of Leiberkuhn or intestinal glands
• Numerous lymphatic follicles
5. What are crypts of Lieberkuhn?
• Intestinal glands or crypts of Lieberkuhn are the invaginations of surface epithelium (simple columnar epithelium) into lamina propria
6. Name the different types of cells in appendix.
• Columnar absorptive cells
• Goblet cells
• Enteroendocrine / APUD cells
• Mucous cells
• Undifferentiated cell
• Paneth cells
• Lymphocytes
7. What is muscularis mucosae?
• Muscularis mucosae is thin layer of smooth muscle arranged as inner circular and outer longitudinal layers around the lamina propria. It is interrupted by the lymphatic follicles extending between lamina propria and submucosa
8. What are the components of submucosa?
• Dense connective tissue
• Larger blood vessels
• Submucosal (Meissner's) plexus of autonomic nerves
• Lymphatic follicles
9. What are the components of muscularis externa? Or what is the arrangement of muscle fibers in muscularis externa?
• Inner circular smooth muscle layer
• Outer longitudinal smooth muscle layer
• Between two layers is thin connective tissue layer with blood vessels, lymph vessels, myenteric (Auerbach's) plexus of autonomic nerves
10. What is serosa?
• Serosa: thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue lined by mesothelium (simple squamous epithelium)
11. What is mesothelium?
• It is a simple squamous epithelium covering a thin layer of loose connective tissue in the abdomen surrounding the viscera
12. What is the function of Meissner's plexus?
• Meissner’s plexus regulates the configuration of the luminal surface, controls glandular secretions, alters electrolyte and water transport and regulates local blood flow
13. List the characteristic features seen only in appendix?
• Plicae circularis, Villi are absent
• Numerous Goblet cells
• Crypts of Leiberkuhn are few
• Muscularis mucosae interrupted due to lymphatic follicles extending between lamina propria and submucosa
14. Difference between serosa and adventitia

Serosa	Adventitia
Thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue covered by mesothelium (simple squamous epithelium)	Loose connective tissue with numerous blood vessels, lymphatics, adipose tissue which merges with surrounding tissues. Mesothelium is absent

15. Name the differences between the small intestine and large intestine.

	Small Intestine	Large Intestine
Mucosa	Plicae circularis and villi present.	Absent.
Epithelium	Goblet cells less in number and columnar cells more in number.	Goblet cells more in number and few columnar cells.
Lamina Propria	Crypts of Leiberkuhn are few and consist of columnar cells, goblet cells, more number of Paneth and argentaffin cells.	Crypts of Leiberkuhn are more numerous, deeper and consists of less number of columnar cells, numerous goblet cells, very rarely Paneth and argentaffin cells.
Muscularis mucosa	Smooth muscle: inner circular and outer longitudinal layers. Interrupted in some regions.	Smooth muscle: inner circular and outer longitudinal layers.
Submucosa	Dense irregular connective tissue with large blood vessels, lymphatic vessels, Meissner’s plexus, glands and lymphatic tissue in some parts.	Dense irregular connective tissue with large blood vessels, lymphatic vessels, Meissner’s plexus, lymphatic tissue.
Muscularis externa	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat uniformly thick.	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat, thickened to form three bands, the taenia coli.
Serosa	Loose connective tissue covered by mesothelium, has blood and lymph vessels.	In some parts absent, which are covered by adventitia.

large intestine / histology / discussion / viva / oral / questions

1. What are the four main layers of large intestine?
• From within (lumen) outwards
• Mucosa (mucous membrane)
• Submucosa
• Muscularis externa
• Serosa or adventitia
2. What are the layers of mucosa?
• From lumen outwards
• Epithelial lining
• Lamina propria
• Muscularis mucosae
3. What is the epithelial lining in large intestine?
• Simple columnar epithelium and numerous goblet cells
4. What is the function of large intestine?
• Water and electrolyte reabsorption
5. Why the goblet cells are more in large intestine?
• The digested food becomes harder and harder as it moves towards large intestine since due to reabsorption of water and electrolytes. Mucus helps the hard substance to move easily further towards anus without damage to the wall.
6. What are the components of lamina propria?
• Loose connective tissue
• Blood vessels
• Lymphatics
• Nerves
• Crypts of Leiberkuhn or intestinal glands
7. What are crypts of Lieberkuhn?
• Intestinal glands or crypts of Lieberkuhn are the invaginations of surface epithelium (simple columnar epithelium) into lamina propria
8. Name the different types of cells in large intestine.
• Columnar absorptive cells
• Goblet cells
• Enteroendocrine / APUD cells
• Mucous cells
• Undifferentiated cell
• Paneth cells
• Lymphocytes
• M cells
9. What is muscularis mucosae?
• Muscularis mucosae is thin layer of smooth muscle arranged as inner circular and outer longitudinal layers around the lamina propria. 
10. What are the components of submucosa?
• Dense connective tissue
• Larger blood vessels
• Submucosal (Meissner's) plexus of autonomic nerves
11. What are the components of muscularis externa? Or what is the arrangement of muscle fibers in muscularis externa?
• Inner circular smooth muscle layer
• Outer longitudinal smooth muscle layer. The muscle fibers are thickened in three places to form bands called taenia coli
• Between two layers is thin connective tissue layer with blood vessels, lymph vessels, myenteric (Auerbach's) plexus of autonomic nerves
12. What are taenia coli?
• Taenia coli are thickenings of outer longitudinal layer of muscularis externa. There are 3 taenia coli which can be traced to root of appendix. 
13. What is serosa?
• Serosa- thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue lined by mesothelium (simple squamous epithelium)
14. What is mesothelium?
• It is a simple squamous epithelium covering a thin layer of loose connective tissue in the abdomen surrounding the viscera
15. What is the function of Meissner's plexus?
• Meissner’s plexus regulates the configuration of the luminal surface, controls glandular secretions, alters electrolyte and water transport and regulates local blood flow
16. What is the function of Myenteric plexus?
• Myenteric plexus supplies the GIT and controls the gastric motility
17. List the characteristic features seen only in large intestine?
• Plicae circularis, Villi are absent
• Numerous Goblet cells
• Crypts of Leiberkuhn are more numerous, connective tissue very less
18. Difference between serosa and adventitia

Serosa	Adventitia
Thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue covered by mesothelium (simple squamous epithelium)	Loose connective tissue with numerous blood vessels, lymphatics, adipose tissue which merges with surrounding tissues. Mesothelium is absent

18. Name the differences between the small intestine and large intestine.

	Small Intestine	Large Intestine
Mucosa	Plicae circularis and villi present.	Absent.
Epithelium	Goblet cells less in number and columnar cells more in number.	Goblet cells more in number and few columnar cells.
Lamina Propria	Crypts of Leiberkuhn are few and consist of columnar cells, goblet cells, more number of Paneth and argentaffin cells.	Crypts of Leiberkuhn are more numerous, deeper and consists of less number of columnar cells, numerous goblet cells, very rarely Paneth and argentaffin cells.
Muscularis mucosa	Smooth muscle: inner circular and outer longitudinal layers. Interrupted in some regions.	Smooth muscle: inner circular and outer longitudinal layers.
Submucosa	Dense irregular connective tissue with large blood vessels, lymphatic vessels, Meissner’s plexus, glands and lymphatic tissue in some parts.	Dense irregular connective tissue with large blood vessels, lymphatic vessels, Meissner’s plexus, lymphatic tissue.
Muscularis externa	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat uniformly thick.	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat, thickened to form three bands, the taenia coli.
Serosa	Loose connective tissue covered by mesothelium, has blood and lymph vessels.	In some parts absent, which are covered by adventitia.

Histology slide identification, How to identify slide in a second

Ileum / histology / discussion / viva / oral / questions

1. What are the four main layers of ileum?
• From within (lumen) outwards
• Mucosa (mucous membrane)
• Submucosa
• Muscularis externa
• Serosa or adventitia
2. What are the layers of mucosa?
• From lumen outwards
• Epithelial lining
• Lamina propria
• Muscularis mucosae
3. What is the epithelial lining in ileum?
• Simple columnar epithelium with striated border and numerous goblet cells
4. What are the modifications of mucosa?
• Plicae circularis, villi, microvilli
5. What are the functions of modifications of mucosa?
• Modifications of mucosa increases the surface area of absorption
6. What are the components of lamina propria?
• Loose connective tissue
• Blood vessels
• Lymphatics
• Numerous lymphatic nodules called Payer’s patches
• Nerves
• Crypts of Leiberkuhn or intestinal glands
7. What are crypts of Lieberkuhn?
• Intestinal glands or crypts of Lieberkuhn are the invaginations of surface epithelium (simple columnar epithelium) into lamina propria
8. What are lacteals?
• Lacteals are dilated blind ending lymphatic capillary present in the core of lamina propria of the villus. It absorbs dietary fats.
9. What are the plicae circularis, villi, microvilli?
• Plicae circularis is the permanent fold of 3 layers of mucosa with core of submucosa
• Villi are the surface projections of epithelial layer with core of lamina propria
• Microvilli are the projections of cell membrane with core of cytoplasm
10. Name the different types of cells in intestinal glands.
• Columnar absorptive cells
• Goblet cells
• Enteroendocrine / APUD cells
• Mucous cells
• Undifferentiated cell
• Paneth cells
• Lymphocytes
• M cells
11. What is muscularis mucosae?
• Muscularis mucosae is thin layer of smooth muscle arranged as inner circular and outer longitudinal layers around the lamina propria. 
• It is interrupted by the Payer’s patches extending between lamina propria and submucosa
12. What are the components of submucosa?
• Dense connective tissue
• Larger blood vessels
• Submucosal (Meissner's) plexus of autonomic nerves
• Numerous lymphatic nodules called Payer’s patches
13. What are the components of muscularis externa? Or what is the arrangement of muscle fibers in muscularis externa?
• Inner circular smooth muscle layer
• Outer longitudinal smooth muscle layer
• Between two layers is thin connective tissue layer with blood vessels, lymph vessels, myenteric (Auerbach's) plexus of autonomic nerves
14. What is serosa?
• Serosa- thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue lined by mesothelium (simple squamous epithelium)
15. What is mesothelium?
• It is a simple squamous epithelium covering a thin layer of loose connective tissue in the abdomen surrounding the viscera
16. What is the function of Meissner's plexus?
• Meissner’s plexus regulates the configuration of the luminal surface, controls glandular secretions, alters electrolyte and water transport and regulates local blood flow
17. What is the function of Myenteric plexus?
• Myenteric plexus supplies the GIT and controls the gastric motility
18. List the characteristic features seen only in ileum?
• Numerous Goblet cells
• Villi are few, short, narrow
• Interrupted muscularis mucosae
• Numerous lymphatic nodules called Payer’s patches extending between lamina propria and submucosa interrupting muscularis mucosae
19. Difference between serosa and adventitia

Serosa	Adventitia
Thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue covered by mesothelium (simple squamous epithelium)	Loose connective tissue with numerous blood vessels, lymphatics, adipose tissue which merges with surrounding tissues. Mesothelium is absent

20. Name the differences between the duodenum, jejunum and ileum?

	Duodenum	Jejunum	Ileum
Mucosa Epithelium	Columnar epithelium with Striated with few goblets cells.	Columnar epithelium with Striated border with more goblets cells.	Columnar epithelium with Striated border with high number of goblets cells.
Villi	Numerous, Tall, broad.	Numerous, Tall, narrow.	Less, Short, narrow.
Lamina propria	Crypts of Leiberkuhn with argentaffin cells. Loose lymphatic tissue.	Crypts of Leiberkuhn with less argentaffin cells. Diffuse lymphatic nodules.	Crypts of Leiberkuhn with less argentaffin cells. Lymphatic nodules aggregated to form Peyer’s patches.
Muscularis mucosa	Continuous.	Interrupted.	Interrupted.
Submucosa	Presence of Brunner’s glands. Connective tissue with blood vessels and nerves.	Connective tissue with blood vessels and nerves.	Presence of Peyer’s patches. Connective tissue with blood vessels and nerves.
Muscularis externa	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels.	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels.	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels.
Serosa	Loose connective tissue with blood and lymph vessels lined by mesothelium.	Loose connective tissue with blood and lymph vessels lined by mesothelium.	Loose connective tissue with blood and lymph vessels lined by mesothelium.

21. Name the differences between the small intestine and large intestine.

	Small Intestine	Large Intestine
Mucosa	Plicae circularis and villi present.	Absent.
Epithelium	Goblet cells less in number and columnar cells more in number.	Goblet cells more in number and few columnar cells.
Lamina Propria	Crypts of Leiberkuhn are few and consist of columnar cells, goblet cells, more number of Paneth and argentaffin cells.	Crypts of Leiberkuhn are more numerous, deeper and consists of less number of columnar cells, numerous goblet cells, very rarely Paneth and argentaffin cells.
Muscularis mucosa	Smooth muscle: inner circular and outer longitudinal layers. Interrupted in some regions.	Smooth muscle: inner circular and outer longitudinal layers.
Submucosa	Dense irregular connective tissue with large blood vessels, lymphatic vessels, Meissner’s plexus, glands and lymphatic tissue in some parts.	Dense irregular connective tissue with large blood vessels, lymphatic vessels, Meissner’s plexus, lymphatic tissue.
Muscularis externa	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat uniformly thick.	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat, thickened to form three bands, the taenia coli.
Serosa	Loose connective tissue covered by mesothelium, has blood and lymph vessels.	In some parts absent, which are covered by adventitia.

Jejunum / histology / discussion / viva / oral / questions

1. What are the four main layers of jejunum?
• From within (lumen) outwards
• Mucosa (mucous membrane)
• Submucosa
• Muscularis externa
• Serosa or adventitia
2. What are the layers of mucosa?
• From lumen outwards
• Epithelial lining
• Lamina propria
• Muscularis mucosae
3. What is the epithelial lining in jejunum?
• Simple columnar epithelium with striated border and goblet cells more than in duodenum
4. What are the modifications of mucosa?
• Plicae circularis, villi, microvilli
5. What are the functions of modifications of mucosa?
• Modifications of mucosa increases the surface area of absorption
6.  What are the components of lamina propria?
• Loose connective tissue
• Blood vessels
• Lymphatics
• Scattered Lymphocytes and occasional lymphatic nodule
• Nerves
• Crypts of Leiberkuhn or intestinal glands
7. What are crypts of Lieberkuhn?
• Intestinal glands or crypts of Lieberkuhn are the invaginations of surface epithelium (simple columnar epithelium) into lamina propria
8. What are lacteals?
• Lacteals are dilated blind ending lymphatic capillary present in the core of lamina propria of the villus
9. What are the plicae circularis, villi, microvilli?
• Plicae circularis is the permanent fold of 3 layers of mucosa with core of submucosa
• Villi are the surface projections of epithelial layer with core of lamina propria
• Microvilli are the projections of cell membrane with core of cytoplasm
10. Name the different types of cells in intestinal glands.
• Columnar absorptive cells
• Goblet cells
• Enteroendocrine / APUD cells
• Mucous cells
• Undifferentiated cell
• Paneth cells
• Lymphocytes
• M cells
11. What is muscularis mucosae?
• Muscularis mucosae is a discontinuous thin layer of smooth muscle arranged as inner circular and outer longitudinal layers around the lamina propria
12. What are the components of submucosa?
• Dense connective tissue
• Larger blood vessels
• Submucosal (Meissner's) plexus of autonomic nerves
13. What are the components of muscularis externa? Or what is the arrangement of muscle fibers in muscularis externa?
• Inner circular smooth muscle layer
• Outer longitudinal smooth muscle layer
• Between outer two layers is thin connective tissue layer with blood vessels, lymph vessels, myenteric (Auerbach's) plexus of autonomic nerves
14. What is serosa?
• Serosa- thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue covered by simple squamous epithelium (mesothelium)
15. What is mesothelium?
• It is a simple squamous epithelium covering a thin layer of loose connective tissue in the abdomen surrounding the viscera
16. What is the function of Meissner's plexus?
• Meissner’s plexus regulates the configuration of the luminal surface, controls glandular secretions, alters electrolyte and water transport and regulates local blood flow
17. What is the function of Myenteric plexus?
• Myenteric plexus supplies the GIT and controls the gastric motility
18. List the characteristic features seen only in jejunum?
• Goblet cells are more than in duodenum
• Villi are tall, narrow and numerous
• Scattered lymphocytes with occasional lymphatic nodules
19. Difference between serosa and adventitia

Serosa	Adventitia
Thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue covered by mesothelium (simple squamous epithelium)	Loose connective tissue with numerous blood vessels, lymphatics, adipose tissue which merges with surrounding tissues. Mesothelium is absent

20. Name the differences between the duodenum, jejunum and ileum?

	Duodenum	Jejunum	Ileum
Mucosa Epithelium	Columnar epithelium with Striated with few goblets cells.	Columnar epithelium with Striated border with more goblets cells.	Columnar epithelium with Striated border with high number of goblets cells.
Villi	Tall, broad.	Tall, narrow.	Short, broad.
Lamina propria	Crypts of Leiberkuhn with argentaffin cells. Loose lymphatic tissue.	Crypts of Leiberkuhn with less argentaffin cells. Diffuse lymphatic nodules.	Crypts of Leiberkuhn with less argentaffin cells. Lymphatic nodules aggregated to form Peyer’s patches.
Muscularis mucosa	Continuous.	Interrupted.	Interrupted.
Submucosa	Presence of Brunner’s glands. Connective tissue with blood vessels and nerves.	Connective tissue with blood vessels and nerves.	Presence of Peyer’s patches. Connective tissue with blood vessels and nerves.
Muscularis externa	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels.	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels.	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels.
Serosa	Loose connective tissue with blood and lymph vessels lined by mesothelium.	Loose connective tissue with blood and lymph vessels lined by mesothelium.	Loose connective tissue with blood and lymph vessels lined by mesothelium.

21. Name the differences between the small intestine and large intestine.

	Small Intestine	Large Intestine
Mucosa	Plicae circularis and villi present.	Absent.
Epithelium	Goblet cells less in number and columnar cells more in number.	Goblet cells more in number and few columnar cells.
Lamina Propria	Crypts of Leiberkuhn are few and consist of columnar cells, goblet cells, more number of Paneth and argentaffin cells.	Crypts of Leiberkuhn are more numerous, deeper and consists of less number of columnar cells, numerous goblet cells, very rarely Paneth and argentaffin cells.
Muscularis mucosa	Smooth muscle: inner circular and outer longitudinal layers. Interrupted in some regions.	Smooth muscle: inner circular and outer longitudinal layers.
Submucosa	Dense irregular connective tissue with large blood vessels, lymphatic vessels, Meissner’s plexus, glands and lymphatic tissue in some parts.	Dense irregular connective tissue with large blood vessels, lymphatic vessels, Meissner’s plexus, lymphatic tissue.
Muscularis externa	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat uniformly thick.	Inner circular and outer longitudinal smooth muscle   layers with myenteric (Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat, thickened to form three bands, the taenia coli.
Serosa	Loose connective tissue covered by mesothelium, has blood and lymph vessels.	In some parts absent, which are covered by adventitia.