Question

Find out the correct sequence in body wall of Ascaris.

• A. Cuticle, epidermis, longitudinal muscles and circular muscles.
• B. Cuticle, epidermis and longitudinal muscles.
• C. Epidermis, cuticle, longitudinal muscles and circular muscles.
• D. Epidermis, longitudinal muscles, cuticle and circular muscles.

Answer 1

The correct option is B Cuticle, epidermis and longitudinal muscles.

The fine structure of the body-wall in Ascaris lumbricoides was investigated by electron-microscopical techniques. The body-wall is composed of a cuticle, epidermis, and a single layer of muscle cells. Epidermis is the outermost syncytial layer covered on the outer surface by cuticle, which is a thick, transparent and noncellular layer secreted by the underlying epidermis. Epidermis is also called hypodermis as it lies below the thick layer of cuticle. Below the skin muscles form a single layer of spindle-shaped cells that line the body cavity. The muscle layer is divided into four longitudinal columns, two dorso-lateral and two ventro-lateral. Circular muscles are altogether absent.

So, the correct answer is 'Cuticle, epidermis and longitudinal muscles.'.