Gill Pouches

Gill Pouches

 

or gill pockets, paired protrusions of the pharyngeal wall, present in all vertebrate animals in the early stages of their development. In cartilaginous fish, the spaces between the gill plates are sometimes called gill pouches. In cyclostomes the gill pouches are part of the gill apparatus that fulfills the function of respiration; there are from six to 14 pairs of them. Each gill pouch is spherical; its mucosa forms folds—the gill lobes. The gill pouches unite with the pharynx (in hagfish) or with a special respiratory tube (in lampreys) by means of an internal canal. The external canals of the gill pouches open to the body surface separately or after prelimi-nary merging (in hagfish).

References in periodicals archive ?
It is further characterized by the combination of the following characters: slime pores--prebranchial 18, branchial 12, trunk 70, caudal 19, total 119; gill pouches (GP) and gill apertures (GA) 12, PCD widely separated from the opening of posterior left GAs; multicusps in anterior row 3 and multicusps in posterior row 2, total cusps 46; paired dorsal nasal sinus papillae; eyespot absent; body coloration pink.
strickrotti resembles 11 of the remaining 24 species of Eptatretus by the 3/2 multicusp configuration, but it differs from all these by the more numerous gill pouches (12 vs.
strickrotti with VA bifurcation close to the anterior gill pouches indicates that this is the plesiomorphic condition for eptatretines.