Histopathology of culture‐associated skin erosions and papillary hyperplasia of Atlantic halibut, Hippoglossus hippoglossus (L.)

Abstract

Atlantic halibut, Hippoglossus hippoglossus (L.), that were cultured in tanks with a smooth bottom (gel-coated fibreglass) substrate developed papillary hyperplasia and skin erosions on the blind (ventral) side. No viruses, bacteria or parasites were observed in any sections of affected skin. Comparison of microscopic pathology with that of skin from normal, wild-caught halibut showed severe epidermal proliferation with foci of severe mucous cell hyperplasia. Both epidermal thickness and mucous cell density were significantly greater in fish held on a smooth substrate compared to skin of healthy fish. Spongiosis was present, especially at the base of the papillary, hyperplastic epidermis, and there was a chronic inflammatory infiltrate in the scale pockets composed of lymphocytes, histiocytes and erythrocytes. Skin erosions had various degrees of epidermal loss, in some cases to the basement membrane. A predisposing factor for the epidermal sloughing may have been related to the spongiosis, and the vacuolated, degenerated basal cells. When affected halibut were cultured for an additional 28, 62 or 97 days on a sand substrate, which is conducive to skin lesion healing, there was no apparent change in epidermal thickness over time. However, mucous cell density significantly increased from day 0 to 97 during the healing process.

Healing of cutaneous wounds in a freshwater teleost, Labeo rohita: Scanning electron microscopical investigation

“…Bereiter‐Hahn (1986) reported that the main factor controlling the cell movement seems to be contact inhibition of motility or contact paralysis, that is, as soon as advancing margins of epidermal sheet come in contact, migration ceases. Quilhac and Sire (1999) has also reported piling up of the epithelial cells after the closure of the wound to form an epidermal fold (= epidermal ridge, present investigation) in the fish H. bimaculatus and suggested that the contact inhibition does not occur immediately. Nevertheless, Silva et al (2004), in N. coriiceps , did not observe epidermal ridge and reported immediate fusion of the migrating epidermis after the contact of the opposing fronts.…”

“…In L. rohita , the epidermal ridge is prominent up to 12 h and thereafter it gradually disappears. Quilhac and Sire (1999) reported that such a fold persists for at least 18 h in H. bimaculatus .…”

“…Despite most of our knowledge on the process of healing of skin wounds in different fish species is based on histopathological studies (for review of literature, see Guerra et al,2008; Iger and Abraham,1990; Silva et al,2005), the reports on the healing of the skin wound using SEM are scanty. Quilhac and Sire (1999) reported the repair of excised wounds in Hemichromis bimaculatus using scanning and transmission electron microscopy. Silva et al (2004) analyzed the kinetic of healing of excised wounds in Notothenia coriiceps at 0°C using SEM.…”

Alterations of Club Cell Activity in Epidermis of Common Carp, <I>Cyprinus Carpio</I> (Actinopterygii: Cypriniformes: Cyprinidae), due to Infection by <I>Ichthyophthirius Multifiliis</I> (Protista: Ciliophora)

“…Mucous cell exhaustion with a reduced number of active cells is often seen as a response to injury (Ottesen et al 2010, Ozerov et al 2010. Contrarily, club cells respond to parasite injuries with an increase in cell size and density.…”

“…The epidermal tissue of fish is often the primary barrier, to pathogens in the environment (Singh and Mittal 1990, Iger et al 1994, Rakers et al 2010, Ottesen et al 2010. The cell-mediated innate mechanisms of epidermal tissues include specialized cells such as macrophages, granulocytes, natural killer cells, and also physical barriers such as mucous layers and skin epithelial tissue lines (Jones 2001, Aoki et al 2008.…”