The demonstration of chloride ions in the “chloride cells” of the gills of eels (Anguilla anguilla L.) adapted to sea water

Two types of chloride cells in the gill epithelium of a freshwater-adapted euryhaline fish: Lebistes reticulatus; their modifications during adaptation to saltwater

Two types of chloride cells were identified in the gill epithelium of freshwater-adapted guppies. One type, referred to as an "alpha-chloride cell," was a pale, elongated cell located at the base of the secondary lamella in close contact with the arterioarterial pillar capillaries. In its cytoplasm, membranous tubules in continuity with its basolateral plasma membrane formed an extended tridimensional network. The vesiculotubular system (Pisam: Anat. Rec. 200:401-414, 1981) consisted of a few tubules and vesicles located next to the apical plasma membrane. A second type, referred to as a "beta-chloride cell," was a darker, ovoid cell located in the interlamellar region of the primary epithelium facing the central venous sinus. Membranous tubules in continuity with the basolateral plasma membrane were unevenly distributed in the cytoplasm. A prominent vesiculotubular system composed of numerous vesicles and tubules was found between the Golgi apparatus and the apical surface. During seawater adaptation, the alpha-chloride cells increased in size and progressively transformed into characteristic "seawater alpha-chloride cells" with a well-developed, regular, tight tubular network and numerous vesicles and tubules of the vesiculotubular system accumulated below the apical pit. The beta-chloride cells underwent a progressive degeneration and disappeared. Thus, in freshwater-adapted guppies, there are two types of chloride cells, alpha and beta, respectively, related to the arterial and the venous vessels, whereas in seawater-adapted fishes, a single type of cell, the alpha-chloride cell, was related to both the arterial and venous channels.

Unusual association of 'chloride cells' with another cell type in the skin of the glass catfish, Kryptopterus bicirrhis

A previously undescribed association of typical 'chloride cells' and a second distinct cell type are observed in the skin of the freshwater glass catfish, Kryptopterus bicirrhis. The second cell type is similar to the chloride cell in that it contains abundant smooth endoplasmic reticulum and mitochondria. However, its small size and greater electron density suggest it is a 'resting' or non-functional chloride cell. Together these two cells form a crypt which leads to the skin surface. They may constitute a specialized structure involved in the passage of ions across the skin of these fish.

Ultracytochemical localization of Na+,K+-activated ATPase in chloride cells from the gills of a euryhaline teleost

The activity of the electrolyte transport enzyme, sodium, potassium-activated adenosine triphosphatase (Na+,K+-ATPase), in the gills of the pinfish, Lagodon rhomboides, increased markedly following transfer of fish from brackish water to seawater. Cytochemical localization of Na+,K+-ATPase via its potassium-dependent phosphatase (K+-NPPase) activity in the branchial epithelium of pinfish adapted to seawater demonstrated that chloride cells are the major sites for the enzyme. Subcellularly, the heaviest depositions of reaction product were observed lining the cytoplasmic membrane surfaces of the labyrinth of anastomosing plasma membrane tubules that ramifies throughout the chloride cell cytoplasm. Enzyme activity was demonstrated also on the cytoplasmic surface of the apical crypt membrane and on the cytoplasmic surfaces of vesicles in the cytoplasm subjacent to the crypt. Deletion of potassium from the cytochemical incubation medium or inclusion of 10 mM ouabain abolished the reaction products associated with these membranes. The significance of these cytochemical results is discussed with reference to current hypotheses of chloride cell function.

From frog skin to sheep rumen: a survey of transport of salts and water across multicellular structures

All higher animals, whether they live in water or on dry land, are faced with the necessity of regulating rather closely their intake and excretion of salts and water in order to maintain the constancy of their internal ionic environment. The kidney is in general the most important organ of the body as far as the excretion of sodium, potassium, chloride and water is concerned, but there are other tissues which also play a part in controlling the ionic balance between the internal and external environments, such as the intestinal mucosa, the skin and urinary bladder in amphibia, the gill epithelium in fishes, the salt gland in marine birds, and the epithelium of the rumen in ruminants. In addition to excretory and absorptive organs of this type, there are others which are secretory and whose function involves the production of fluids differing in ionic composition from the blood plasma. Examples include the glands which secrete saliva and sweat, the oxyntic acid-producing cells of the gastric mucosa, and the epithelium of the stria vascularis which generates the potassium-rich endolymph of the mammalian cochlea. The purpose of this article is to consider briefly what is known about the active transport of salts and water across some typical multicellular secretory tissues, and to attempt in the process to discern what properties they have in common and in what respects they are specialized.