Notes: Excised liver sections of the milkfish, Chanos chanos, fry and fingerlings were studied by transmission electron microscopy. The hepatocytes underwent marked ultrastructural alterations in response to food deprivation of 10-day starvation for fry and 2 months for the fingerlings. The prominent features characterizing the hepatocytes of starved fish were: a reduction of cell and nucleus size; apparent loss of nucleoli; condensation of chromatin material in fry; loss of stored glycogen; reduction of ER profiles; increase in the number of electron-dense bodies containing large amounts of iron in fingerlings; and an increase in mitochondrial size. These changes were reversible following short periods of re-feeding, i.e. 2 days for fry and 4 days for fingerlings, using natural food for the fry and formulated diet for the fingerlings.

Notes: In einem vergleichenden Fütterungsversuch wurden Coregonenlarven mit Nauplien des Artemia-Stammes Great Salt Lake/Utah beziehungsweise San Francisco Bay gefüttert. Trotz sehr geringer Mortalitäten in beiden Fütterungsansätzen konnten die Gruppen anhand der Ultrastruktur des Darmepithels eindeutig unterschieden werden. Coregonenlarven, die mit Nauplien des Artemut-Stammes Great Salt Lake gefüttert worden waren, hatten große Mengen Bakterien im Darm und zeigten Schädigungen der Darmschleimhaut von unterschiedlichem Schweregrad. Die Ergebnisse wurden im Vergleich zu Darmepithelveränderungen bei Fischen diskutiert, die anderweitig verursacht wurden, sowie zu bakteriellen Darminfektionen bei Säugetieren.〈section xml:id="abs1-2"〉〈title type="main"〉SummaryDamage to the intestinal epithelium of coregonid larvae (Coregonus fera) due to Artemia feeding: A bacterial infectionIn a comparative feeding experiment coregonid larvae were fed with nauplii of Artemia strain Great Salt Lake/Utah and San Francisco Bay, respectively. Though very low mortalities were observed the different feeding groups can be distinguished by means of the ultrastructure of the intestinal epithelium. Coregonid larvae fed with nauplii of Artemia strain Great Salt Lake/Utah had a lot of bacteria in the intestine and showed damage to the intestinal epithelium in different extent. The results were discussed in comparison with alterations of the intestinal epithelium of fish caused by other factors as well as with bacteria! intestinal infections in mammals.〈section xml:id="abs1-3"〉〈title type="main"〉Résumé Lésion de l'épithélium intestinal des larves de corégones (Coregonus fera) causée par une alimentation sà base d'artémia: une infection bactérielleDans une expérience comparative des larves de corégones ont été nourries avec des nauplius de la souche Great Salt Lake/Utah et San Francisco Bay d'artémia, respectivement. En dépit d'une faible mortalité les deux groupes d'alimentation pouvaient être clairement différenciés sà l'aide de l'ultrastructure de l'épithélium intestinal. Les larves de corégones nourris avec des nauplius de la souche Great Salt Lake/Utah d'artémia avaient beaucoup de bactéries dans l'intestin et montraient des lésions sur la muqueuse intestinale sà des degrés différents. Les résultats ont été discutés et comparés avec les altérations de l'épithélium intestinal chez les poissons causées par d'autres facteurs et aussi avec les infections bactérielles intestinales chez les mammifères.

Notes: The influence of water-borne iron (500 μg × 1-1 and 2 mg × 1-1) on the liver of Poecilia reticulata is studied by means of electron microscopy. The uptake and effect of iron is affected by a. the chemical speciation of the metal: Iron complexed with tri-polyphosphates is more deleterious than inorganic Fe3+; b. the nutritional status of the fish: In food-deprived Poecilia reticulata iron is absorbed and enhances starvation-induced liver damage. In fed animals, there is no uptake at all. Mild alterations of hepatocyte ultrastructure are attributed to an unspecific stress response.

Notes: Zebrafish (Brachydanio rerio) fed diets free of ascorbic acid (vitamin C) or suplemented with 200 mg/kg ascorbic acid for 12 weeks were compared with respect to macroscopically detectable symptoms of pathology and cytoloical alterations of hepatocytes. Fish fed the ascorbic acid-free diet displayed symptoms of scurvy including hemorrhages, fin erosion, and darker pigmentation. Hepatocytes of male zebrafish developed steatosis, whereas liver cells of female zebrafish were free of microvesicular lipid accumulation within the endoplasmic reticulum cisternae, indicating the presence of sex-dependent protection mechanisms against ascorbic acid depletion. Female fish showed a reduction of hepatocellular size and a less regular arrangement of the rough endoplasmic reticulum; hepatocellular glycogen depletion as well as induction of smooth endoplasmic reticulum were characterstic of hepatocytes in either sex. Since zebrafish fed the diet supplemented with ascorbic acid were free of pathological alterations in both external appearance and hepatocellular ultrastructure, results indicate that ascorbic acid not only plays a key role in collagen biosynthesis, but also fulfills central functions in the maintenance of a well-equilibrated lipid metabolism in fish. Accumulation of oxidative reagents represents one possible mechanism leading to hepatocellular steatosis in fish.

Notes: This study was undertaken to identify the normal ultrastructural features of gills and skin of the Senegal sole, Solea senegalensis, for a comparative measure to morphological alterations caused by environmental stressors such as reduced water quality and diseases. In the Senegal sole skin, four morphologically distinct layers were identified: cuticle, epidermis, dermis and hypodermis. The epidermis was composed of stratified epithelium containing three cellular layers: the outermost or mucosa layer, the middle or fusiform layer and the stratum germinativum or the basal layer. In the mucosa, two mucous cell types were differentiated: type A cells containing several round vesicles of different electron density and type B cells containing mucosomes of uniform electron density. Senegal sole have five pairs of gill arches, each containing two rows of well-developed and compactly organized primary filaments and secondary lamellae. Fingerprint-like microridges were observed on the surface of epithelial cells. The branchial lamellae epithelium consisted of different cell types: pavement, mucous and chloride. Between the chloride cells and the larger pavement cells, accessory cells were observed. Complexes of tight junctions and desmosomes were frequently observed between adjacent chloride and epithelial cells. Neutral mucosubstances and/or glycoconjugates were observed in the epidermis, dermis and hypodermis of S. senegalensis skin. Proteins rich in different amino acids, such as arginine and cysteine, reacted negatively or weakly positive in the epidermis, dermis and hypodermis. In gills, some mucous cells responded weakly positive to periodic acid-Schiff (PAS) reaction but were strongly stained with Alcian Blue at pH 0.5, 1 and 2.5. When Alcian Blue pH 2.5–PAS reaction was performed, most mucous cells were stained blue (carboxylated mucins) and some mucocytes stained purple, indicating a combination of neutral and acid mucins. Proteins rich in cysteine-bound sulphydryl (-SH-) and cystine disulphide (-S-S-) groups were strongly detected in branchial and epidermal mucous cells, whereas lysine, tyrosine and arginine containing proteins showed very weak staining in both epidermal and branchial mucous cells. Protein reactions were strongly positive in the pillar cells, except for those rich in tryptophan, whereas the branchial cartilaginous tissue did not show an important reaction. The performed lipid reactions were negative in goblet and chloride cells. It is concluded from this study that ultrastructural and cytohistochemical features of the Senegal sole skin and gills may serve as control structures in both natural and aquaculture systems to monitor or detect environmental stress responses at the histological level.

Notes: The intestinal epithelium of Senegal sole, Solea senegalensis Kaup is composed of three main cell types: epithelial, goblet and rodlet. The cytoplasm of columnar epithelial cells – enterocytes – has spherical lipid droplets. The dominant feature throughout the intestinal mucosa was goblet cells filled with numerous mucous droplets of high density. The cytoplasm of the rodlet cells contained peripheral filamentous, pycnotic nuclei, and numerous cytoplasmic inclusions (rodlets), with a very dense cylindrical core surrounded by flocculent material. Some physiological implications related to ultrastructural features of the intestine are also discussed.