Abstract

ZACARIAS, M; CADENA, M  and  RIVAS, P. Structural Modifications in the Stomach and Liver of Paralabrax maculatofasciatus (Steindacher, 1868) under Chronic Stress Conditions. Int. J. Morphol. [online]. 2009, vol.27, n.2, pp. 425-433. ISSN 0717-9502.  doi: 10.4067/S0717-95022009000200019.

To determine stress effects at histological level in the digestive system, organisms of Paralabrax maculatofasciatus were submitted to 2 stress models. One of decreasing the water level (n=84) for 30 and 60 min daily, and another at high density cultures (n=96) of 1.6 and 3.2 Kg/1001. Stomach and the liver samples were fixed in 10% formalin, embedded in paraffin wax, sectioned at 6 urn and stained with haematoxylin-eosin. In both stress conditions, the stomach showed important morphological changes in the mucosa layer, such as hypertrophy and atrophy. In the liver, coloration and texture changes were observed as well as haemolisis, inflammation and necrosis. In the water decrease model, the mucosa layer of stomach showed significant morphometric differences (P<0.05), between different times of stress exposure and/or between different days, in some of the measured parameters. In the high-density model, significant differences in the stomach mucosa showed a sampling-density interaction in 4 parameters and 6 other parameters showed differences with no interaction. Liver showed significant differences in nuclear perimeter between sampling-days. Stress caused by high-density culture proved to be the factor that caused the most serious tissue damage.

Keywords : Stress; Paralabrax maculatofasciatus; Histophatology.