A. Upper part is lined by stratified columnar epithelium.
B. Upper part contains anal columns of morgagni.
C. Middle part is below Hilton’s line.
D. Middle part contains sweat and sebaceous glands.
Ans;B. Upper part contains anal columns of Morgagni.
The organ marked by a red box in the picture above represents the anal canal.
Feature of epithelium of anal canal is that the upper part contains anal columns of margagni.
The interior of anal canal is divided by pectinate line and Hilton’s white line into three parts.
1. Upper part (mucous part)
- It is upper 15 mm part of anal canal and extends upto pectinate line. It is lined by mucous membrane which is simple columnar. Mucosa shows 6-10 longitudinal folds called anal columns of Morgagni. Lower ends of these folds are united by short transverse folds, anal valves.
- Line of attachment of anal valve is known as pectinate line or dentate line. Slight depression above each anal valve is known as anal sinus.
2. Middle part (transitional zone or pecten)
- This area is 15 mm in extent and intervenes between pectinate (dentate) line and Hilton’s white line. It is lined by non-keratinized stratified squamous epithelium without sebaceous and sweat glands.
3. Lower part (cutoneous) part
- It is about 8 mm in extent and is lined by true skin, i.e. stratified squamous keratimizing epithelium with sebaceous and sweat glands.