Cellular responses in the skin of the trout (Oncorhynchus mykiss) exposed to temperature elevation

Abstract

The skin of rainbow trout was examined at the ultrastructural and cytochemical level after a 3-h exposure to an elevation of the water temperature, from 15 to 22° C. Within 3 h, the thickness of the epidermis had significantly (P <0 05) decreased when compared to control fish. After 24 h it was restored, and from day 4 onwards even increased above control levels. The thickening of the epidermis was associated with appearance of many mitotic cells, not observed in control fish. Within 24 h many apoptotic epidermal cells were found, indicating enhanced ageing of the cells. Filament cells from the outer epidermal layers synthesized vesicles with peroxidase activity within 3 h after temperature elevation. This enzyme was found also in apoptotic as well as in necrotic filament cells. Mucous cells became elongated and their mucosomes displayed peroxidase activity. Occasionally electrondense, probably serous, mucosomes appeared. In the epidermis rodlet cells were found. Both epideimis and dermis, became invaded by many lymphocytes and macrophages. The latter contained vesicles with peroxidase activity. Pigment-containing cytoplasmic extensions of melanocytes penetrated the epidermis while iridocyles disappeared from the dermis. The synthetic activity of dermal fibroblasts was stimulated. These results show that a moderate temperature elevation has pronounced and prolonged effects on the skin of the exposed fish. The effects are to a high extent comparable with those of stressors such as heavy metals, acid water or wounding.

Cortisol Induces Stress-Related Changes in the Skin of Rainbow Trout (Oncorhynchus mykiss)

“…The ultra structure of the skin of control rainbow trout has been described before (Iger et al, 1994b). The epidermis of the controls was about 110-135 |xm thick and composed of filament-containing epithelial cells (fila ment cells) with typical pavement cells, characterized by apical ridges, at the inter face with the water (Fig.…”

Reaction of rodlet cells to a myxosporean infection in kidney of the bluegill, Lepomis macrochirus

“…Courtney and Couch (1988) exposed sheepshead minnows to the carcinogen N-nitrosodiethylamine and noted increased levels of rodlet cells in the liver concurrent with the development of neoplasias and during recovery from the induced acute hepatic cytotoxicity . Iger and Abraham (1990) studied skin healing following superficial wounding in mirror carp and reported that rodlet cells moved into the region of the wound site within 1 h. Iger et al (1994) noticed that epidermal rodlet cells were elevated in rainbow trout 4 days after skin injury produced by an acute rise in temperature from 15 to 22 OC. These authors also reported increases in peroxidasecontaining granules in mucous cells, filament cells, and macrophages, and peroxidase staining in the secretory granules of rodlet cells.…”

The first appearance of Rodlet cells in carp (Cyprinus carpio L.) ontogeny and their possible roles during stress and parasite infection

“…Exposure to heavy metals [27e29], N-nitrosodiethylamine [30] or thermal elevation [31] induced increased number of RCs in various target tissues. This suggests a function in stress physiology and thus RC numbers may be useful as biomarkers for stressors and chemical agents [9,22].…”