Dr. ANAND SRINIVASAN

Able to : Describe, identify and draw the

histological features of : Small intestine Large intestine Rectum & Anal canal

Divided into duodenum, jejunum and ileum

Luminal surface is increased for absorption by Plica circulares (valves of Kerckring) Intestinal villi Microvilli

MUCOSA EPITHELIUM▪ Simple columnar epithelium with goblet cells ▪ Epithelium and lamina propria form intestinal

villi▪ Presence of glycocalyx for protection and

adsorption of pancreatic enzymes. ▪ Crypts of Lieberkuhn containing goblet cells,

columnar cells and Paneth cells▪ Paneth cells secrete lysozyme, located in base

LAMINA PROPRIA▪ Connective tissue

MUSCULARIS MUCOSA▪ Same as Gen. plan of GIT

SUBMUCOSA Shows regional variation Duodenum Brunner’s gland Ileum Peyer’s patches Jejunum None of the above

MUSCULARIS EXTERNA Same as Gen. plan of GIT

SEROSA Same as Gen. plan of GIT

Leaf like villi

Brunner’s glands (mucous, branched, coiled tubular) in submucosa opening into crypts.

Enteroendocrine cells secrete Urogastrone – inhibit HCl Secretin & Cholecystokinin – regulate

pancreatic secretion

Disrupted muscularis mucosae

Finger like villi

No glands or lymphatic nodules in submucosa

Thin and slender villiPeyer’s patches (aggregated

lymphatic follicles) in submucosa

Consists of Caecum, Appendix, Colon, Rectum and Anal canal

Absence of intestinal Villi

Has bacteria responsible for synthesis of Vitamin B12 & Vitamin K

Produces plenty of mucus that lubricates and facilitates easy passage of faeces

Gen. histological features of small intestine with following modifications No Villi Few short crypts Small lumen Lymphoid follicles in lamina propria Disrupted muscularis mucosae

Gen. histological features of small intestine with following modifications No Villi Well developed crypts with plenty of

goblet cells Paneth cells Absent Outer longitudinal layer of muscularis

externa modified into “Taenia coli” Fat filled pockets in serosa “Appendices

epiploicae”

Gen. histological features of small intestine with following modifications Long crypts of Lieberkuhn Lymphoid tissue less abundant in lamina

propria Absent Taenia coli Serosa replaced by adventitia in lower

part

Gen. histological features of small intestine with following modifications EPITHELIUM▪ Above anal valves – stratified cuboidal▪ At anal valves – stratified squamous non

keratinized▪ At anal orifice – stratified squamous keratinized

No crypts, No muscularis mucosae Inner circular layer thick anal sphincter Smooth muscle changes to skeletal muscle at

orifice

Wheater’s Functional Histology

Cell Biology & Histology – Board Review Series

Microanatomy workbook – RAKMHSU