Protein and carbohydrate histochemistry in relation to the keratinization in the epidermis of Barbus sophor (Cyprinidae, Pisces)

Histochemistry and functional organization of the dorsal skin of Ancistrus dolichopterus (Siluriformes: Loricariidae)

The structural organization and histo-cytochemical features of dorsal skin of Ancistrus dolichopterus (acari bodo) are the main focus of this work. The epidermis, dermis and subcutis are the principal layers of the skin. The epidermis mainly consists of epithelial and mucous cells. Interspersed between them are lymphocytes, pigment cells, eosinophilic granular cells (EGC), and the taste buds as sensory structures. The high number of EGCs is implicated in general and specific immunological defense from pathogenic bacteria and multicellular parasites. The epithelial cells and mucous cells contain glycoproteins with oxidizable vicinal diols, carboxyl groups and O-sulphate esters and their high secretory activity is correlated with the bottom dwelling habit of this species. A thick stratum laxum contains overlapping osteoderms bearing denticles, and the stratum compactum make the integument thicker to help the fish in negative buoyancy for maneuvering near the bottom and protection. The entire body surface is covered by conical, backwardly directed denticles. These are composed of a dentine cone, surrounding a pulp cavity with the top covered by mineralized cap, and are the true homologues of teeth. These structures provide effective protection from abrasion and enemies. These structural peculiarities and histochemical features indicate additional physiological role of the skin of A. dolichopterus.

Studies on the structure and histochemistry of the epidermis in the marine catfish Plotosus lineatus (Thunberg, 1791) (Plotosidae, Pisces)

The structure and the histochemical characteristics of the epidermis of the marine catfish Plotosus lineatus were determined with a series of recent techniques employed either alone or in combination with other procedures to detect selectively sialic acid containing glycoproteins or other acidic carbohydrates. The epidermis consists of a multilayered epithelium where are recognizable various cell types namely, the epithelial cells, the club cells and the mucous or goblet cells the latter concentrated mainly in the outermost layer. The goblet cells and the epithelial cells in the outer epidermis produced both neutral and acidic glycoproteins. The epithelial cells store also acidic glycoproteins containing high amounts of sulphate esters (sulphomucins). The absence of the sialic acid is also discussed.

Mucosaccharide histochemistry and histoenzymorphologic observations on the epidermis of Ariosoma balearicum de la Roche (Anguilliformes, Pisces)

The epidermis of Ariosoma balearicum consists of three layers - the basal layer, the middle layer and the outer layer. In between the basal cells are found clusters of small lymphocytes which show a moderat acid phosphatase activity. The middle layer and the outer layer are composed of three types of cells - the polygonal cells, the mucous cells and the club cells. The mucosubstances within the mucous cells exhibit the properties of neuraminic acid containing mucosaccharides with vicinal hydroxyl, sulfate esters and carboxyl groupings. The superficial cells of the outermost layer are capable of secreting sulphated and carboxylated mucosubstances to form an extracellular mucous coating which in fish epidermis seems to be necessary for the accumulation of electrolytes. The club cells are generally provided with one nucleus or double nuclei which appear displaced from the center and constitute the main histological component of the middle layer. The contents of these cells, in addition to a strong protein uptake visualized by the positive reactions exhibited in the coupled tetrazonium and mercuric bromophenol blue preparations, gave positive response to neutral mucosubstances which appear to be a glycoprotein involved in the slime secretions. Alkaline phosphatase and TPP-hydrolysing enzyme which could be detectable in the basal layer and the basement membrane were correlated with the probable role that they could play in the transportation of various chemicals and nutriments through the cell membranes.