Anatomy of finfish and shellfish

Unit 6 - Respiratory system in fishes

6.2.5. Gill Filaments (Primary gill lamellae)
Each hemibranch consists of both primary and secondary lamellae. The primary gill filaments remain separated from the branchial septum at their distal end making two hemibranch in opposition which direct the water flow between the gill filaments. Amongst duel breathers the heterogeneity in the gill system is more pronounced particularly in the swamp eel, Monopterus, Amphipnous cuchia and climbing perch, Anabas testudineus. In Monopterus gill filaments are stumpy and are present only in second pair of gill and lack gill lamellae. According to Munshi and Singh (1968,a) and Mnshi et al,(1990), the remaining three pairs are without functional lamellae. It is the modification for another way of exchange of gases.
The gill filaments are blad-like structures supported by gill rays. The heads of the gill rays of both the hemibranchs are connected by ligaments (Yadav et al. 1993). They provided with two types of adductor muscle units in teleosts. The gill filaments are also lined by epithelium referred to as primary epithelium. The epithelium has glandular and non glandular part.