secondary lamellae

synonym: respiratory lamellae
https://doi.org/10.1351/goldbook.15020
Parallel rows of projections on the dorsal and ventral sides of each primary lamella of the fish gill. They are the primary sites of gas exchange of the gills.
Source:
PAC, 2009, 81, 829. (Glossary of terms used in ecotoxicology (IUPAC Recommendations 2009)) on page 943 [Terms] [Paper]