No abstract

The organogenesis of ballan wrasse, Labrus bergylta, Ascanius, 1767 larvae was studied during the first 49 days after hatching (DAH) with histological and histochemical methods. During the yolk sac stage (0-9 DAH), a syncytial layer had surrounded the yolk sac. At mouth opening, we distinguished a primordial liver and swim bladder, a buccopharyngeal cavity with gill arch cartilages, an exocrine and endocrine pancreas, and a primordial gastrointestinal tract. By the end of this stage, the heart had become functional, the swim bladder had dilated, olfactory organs and otoliths had developed, the pituitary gland and thyroid follicle could be distinguished, and the eye had become pigmented. During preflexion (10-25 DAH), the swim bladder had inflated, and the renal corpuscles and tubules had joined the collecting duct towards the urinary bladder. Mucous cells were observed, which may provide secretions that protect against abrasion and pathogens, and the density of these cells increased in the buccopharyngeal cavity and oesophagus. During flexion (26-33 DAH), secondary lamellae had developed. Increasing functionality of the digestive system coincided with a shift to the appearance of AB-positive mucous cells in the gill openings and the digestive tract. In addition, pharyngeal teeth had developed, which suggested that food preferences might change to include hard-bodied prey. Stage 4 was mainly characterized by increases in the size and complexity of pre existing organs and structures. At 49 DAH, metamorphosis was complete. The temporal sequence of development of the various systems may provide baseline information for aqua culturists and fish biologists in future studies on fish health, feed, feed development, and cultivation of ballan wrasse.

By using a simple standardized questionnaire, H. pylori serology and a hemoglobin reading in the evaluation of dyspeptic patients under 45 years of age, the need for endoscopy can be reduced by 55%.

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.

Groups of sexually immature juvenile Arctic charr (Salvelinus alpinus L.) were subjected to exercising regimes equivalent to either ~0.0 (control), 1.0, or 2.0 body lengths per second for 63 days. The effects of the different treatments on the epidermal structure of individual fish were examined. Epidermal thickness, measured in micrometres, did not vary between treatments, but fish exposed to a water current equivalent to 2.0 body lengths/s had increased numbers of epidermal cell layers compared with control fish. There were no differences in the numbers of mucous cells per millimetre of cell layer irrespective of the treatment employed, but the increase in the numbers of cell layers exhibited by exercised fish appeared to have resulted in an increase in the numbers of mucous cells per square millimetre of cross-sectional epidermal area (i.e., cell concentration). The superficial mucous cells were significantly larger in exercised fish than in control fish. There were no differences in the sizes of the underlying mucous cells among treatments. The variations in epidermal structure could not be ascribed to differences in individual growth parameters, but appeared to be a consequence of the different exercising regimes imposed upon the fish.