Response of club cells in the skin of the carp Cyprinus carpio to exogenous stressors

Abstract

Vbstract. The ultrastructure of club cells and n eig h b o u r l y filament cells and leucocytes in the epiderm is of carp, vas studied under norm al conditions and after exposure o several stressors: acid water, heavy metals, organic nanure, brackish w ater and w ounding. The effects of the stressors were rem arkably similar. T he club cells in creased in size and contained m ore endoplasm ic reticuum and Golgi areas. In both control and stressed fish, most m itotic figures of the filament cells were found ad ja cent to club cells, as was d em o n strated after colchicine injection. W hereas in the controls apoptosis of filament cells was scarce and limited to the upper layer of the epithelium , in the stressed fish it was com m only seen in close proxim ity to the club cells but not in other mid-epiderm al parts of the epithelium. This indicates th at club cells influence the cellular kinetics of the filament cells. U nder stress conditions leucocytes infiltrated the epider mis. Som e were seen inside club cells. A pparently these leucocytes were taken up in phagosom es and su b seq u en t ly they show ed signs of necrotic degeneration. Leucocyte incorporation and degeneration in club cells were not observed in control fish. C ontrol of the cellular turnover of filament cells and the elim ination of leucocytes m ay represent new functions for club cells, which have m ainly been associated with the production of pherom ones.

Do fathead minnows, Pimephales promelas Rafinesque, alter their club cell investment in responses to variable risk of infection from Saprolegnia?

“…(in press) documented a similar reduction in club cells for minnows exposed to ultraviolet radiation. Iger, Abraham & Wendelaar Bonga (1994) reported that mitotic and apoptotic activity in fish exposed to stress was mainly restricted to cells surrounding mature club cells, whereas in control fish, mitotic and apoptotic activity was scarce and limited to the upper layer of the epithelium. There is evidence that club cells of fish may be involved in phagocytosis and lysis (breakdown of cellular membrane) of leucocytes (Iger et al.…”