BODY WALL OF PERIPLANETA
The body wall of periplaneta consists of
outer – cuticle , middle – epidermis and inner – basement membrane.
1) CUTICLE :-
The body of cockroach is covered by chitinous cuticle. It consists of three layers , namely , an outer – epicuticle , middle –exocuticle and an inner – endocuticle.
- This is a thin nonchitinous layer present on the entire body surface of three parts , they are outer –lipoprotien cement layer , middle – wax layer and an inner – layer of polyphenols.
- It lacks chitin.
II. Exocuticle :–
- It is the middlae layer of the cuticle. It forms sclerites.
- The rigidness of the sclerites is due to the polymerization.
- The cuticle between the segments of the body and at the joints of appendages is soft and flexible due to the absens of the rigid exocuticle in it. But it has only epicuticle and endocuticle. This cuticle is called arthroidal membrane. It allows the bending movements of the appendages at the joints.
- Exocuticle is pigmented.
III. Endocuticle :-
- It is the inner layer of the cuticle.
- It consists of several layers of chitin.
- Endocuticle does not undergo sclerotisation and is lysed just before each moulting or ecdysis.
2) EPIDERMIS :-
- A layer of columnar epithelial cells called epidermis is present below the cuticle.
- The cells of epidermis are functionally and structurally different types. They are
- Columnar epidermal cells – these are glandular and secrete the cuticle. Some of these cells secrete enzymes that lyse the endocuticle during moulting.
- Trichogen cells – form movable bristles .
- Tormogen cells – form the sockets in which the movable bristles are buried.
- Oenocutes – secrte the wax layer of the epicuticle . These are the sunken epidermal cells.
3) BASEMENT MEMBRANE :-
The basement membrane consists of a thin layerof connective tissue and forms the inner most layer of the body wall.