Body Wall

-:Body wall of Nereis:-

The body wall is divisible into -
(a) Cuticle.               (b) Epidermis.
(c) Muscles layers. (d) epidermis.


(a)Cuticle:-
It is thin, slightly brittle and chitinous,non cellular. A number of minute openings are present on the cuticle through which the epidermal gland open to the exterior.
(b) Epidermis:-
This is formed by a single layer of cells. It is more thick on the ventral side specially near the parapodial joints. The dorsal side of the epidermis is richly supplied with blood vessels. Numbers of 'twisted' unicellular glands are present specially on the ventral side.
(c) Muscle layers:-
The outer muscular layer is circularly arranged and the inner layer runs longitudinally. The longitudinal muscles are present in four bundles - two  are dorso-lateral the remaining two are ventro-lateral . The circular muscle of dorsal and ventral sides are interconnected by two strands of oblique muscle.
(d) Parietal epithelium:-
It is a part of the coelomic epithelium which lines the outer wall of the coelom or body cavity. It is made ip of a single layer of cells. It is also called as peristomium.
Function of body wall:-
>Protection against dessication and mechanical injury.
>Help in respiration.
>Help in movement