Question

Peritrophic membrane lines the
(A) Midgut internally
(B) Midgut and Foregut
(C) Hindgut
(D) Foregut
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only
• B. (A) only
• C. (B) only
• D. (B) and (D) only

Hint:

The midgut is the only section of the insect gut without a cuticular lining. It relies on the peritrophic membrane for protection against abrasion and pathogens.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The digestive tract of insects is divided into the foregut (stomodeum), midgut (mesenteron), and hindgut (proctodeum).
The foregut and hindgut are ectodermal in origin and are lined internally by a protective cuticular layer called the intima.
Detailed Explanation:
- The midgut is endodermal in origin and lacks a cuticular intima.
- To protect its delicate epithelial cells from mechanical damage by ingested food and from pathogens, the midgut is lined internally by a semi-permeable, non-cellular sheath called the peritrophic membrane (A).
- This membrane is composed of a network of chitin microfibrils and proteins. It acts as a physical barrier while allowing digestive enzymes and nutrients to pass through.
- The foregut and hindgut do not have a peritrophic membrane because they are already protected by their cuticular intima.
Therefore, the peritrophic membrane lines only the midgut internally.

Step 2: Final Answer:
The peritrophic membrane is found only lining the midgut internally, corresponding to statement (A) only (option 2).