Caption: Fresh water convict cichlid (Cichlasoma nigrofasciatum) - fish gills. Shown here are the fish gill arches with many branchial filaments and respiratory gill lamellae. The surfaces of the gill lamellae are covered with a thin layer of epithelial cells (not shown). Gill lamellae consist of mostly 'pavement' cells (epithelial ridged cells), which are the major site of gas exchange. Mitochondria rich cells (MRC) are produced in the gill lamellae and increase the sonoregulatory capacity in response to osmotic challenges. MRCs are believed to be the site of ion uptake by fish in fresh water. Gills of vertebrates are developed in the walls of the pharynx along a series of gill slits opening to the exterior. In fish, the gills are located on both sides of the pharynx. Gills are made of 'branchial' filaments and respiratory gill lamellae that help increase surface area for oxygen exchange. In bony fish, a bony cover called an operculum covers the gills. When a fish breathes, it opens its mouth at regular times and draws in a mouthful of water. It then draws the sides of its throat together, forcing the water through the gill openings. The water passes over the gills to the outside. Valves inside the mouth keep the water from escaping through the mouth again. In most fish species, a countercurrent exchange system is employed to enhance the diffusion of substances in and out of the gill (i.e. blood and water flow in opposite directions to each other). Water taken into the mouth passes out of the slits, bathing the gills as it passes. Some fish utilize the gills for the excretion of electrolytes.
Magnification*: x20
Type: SEM
Copyright 2009 Dennis Kunkel Microscopy, Inc.
Keywords: 25193A,miscellaneous vertebrates,fish,convict cichlid,zebra cichlid,cichlid,Hawaii,Cichlasoma,Cichlasoma nigrofasciatum,08.01.09,gas exchange,oxygen exchange,aquatic respiration,gill lamella,gill lamellae,respiratory gill lamella,respiratory gill lamellae,misc. vertebrate,misc. vertebrates,miscellaneous vertebrate,fish gill,fish gills,gill,gills,SEM,fishes,freshwater,fresh water,bony fish,visible gills,breathing gills,fish respiration,fish breathing,gill arch,gill arches,respiratory lamellae,branchia,branchiae,branchial filament,branchial filaments,electrolyte excretion,bony fishes,gill filament,gill filaments,operculum,respiratory lamella,gill slit,gill slits,epithelial cell,epithelial cells,epithelium,epithelia,pavement cells,epithelial ridged cells,epithelial ridged cell,mitochondria rich cell,mitochondria rich cells,MRC,osmotic exchange,ion uptake,ion extrusion,ion excretion,epithelial ridged-cells,pavement cell,cichlid fish,vertebrate,vertebrates