Atrium of Branchiostoma (With Diagram) | Chordata | Zoology
The atrial cavity or atrium is an extensive space lined with ectoderm. It is formed by a pair of metapleural folds one on either side above gill-slits of embryo, growing down and getting united ventrally by a transverse shelf so that a portion of the outside space becomes enclosed within the body (Fig. 6.6.). The atrium forms a large cavity [...]