Alterações do epitélio branquial e das lamelas de tilápias (Oreochromis niloticus) causadas por mudanças do ambiente aquático em tanques de cultivo intensivo

Abstract

The behavior of the gill epithelium of tilapias cultured in tanks at different altitudes and interconnected with PVC pipes was analyzed. Gill filaments of four specimens from four tanks (T 1 , T 2 , T 3 e T 4 ) sequentially interconnected were submitted to histological routine to obtain 5-mm-thick cuts that were stained with HE or submitted to histochemistry reactions PAS + diastase solution or Alcian Blue pH 2.5 or Alcian Blue pH 1.0. Considering the intermediary, apical and basal regions of the filaments, the lamellar area was measured and the amount of mucous cells was counted. It was verified that oxygen, pH, and temperature decreased progressively as the water flew from one tank to another. Thus, an increase was realized of the amount of mucous cells and the lamellar area in T 2, as well as a progressive decrease of these measures on the tanks which received water from T 2 . Moreover, detachment of the gill epithelium, cellular hyperplasia in the interlamellar space, and telangectasias were observed in the fishes from T 2 , T 3 e T 4. It was concluded that the aquatic environment in tanks sequentially interconnected with PVC pipes suffers alterations from one tank to another, as that physico-chemical fluctuations reflect on the behavior of the gill epithelium through variations of the lamellar area and the amount of mucous cells.

Morpho-functional response of Nile tilapia (Oreochromis niloticus) to a homeopathic complex

“…53 In fish of the T3, a greater quantity of fluid mucus covered the branchiae compared to that of other animals in the control group and other treatment groups. These data corroborate with results observed by, 51 who emphasised that a more fluid mucus was indicative of a greater interactivity of the branchial epithelium with the water environment.…”

“…52 Research on the population density of mucosal cells from the branchial epithelium of Nile tilapia showed that other factors (aside from the physical and chemical properties under analysis), such as parasites and toxic agents in the sediments, may affect the number of mucosal cells in the findings described above. 51 When compared with the number of neutral mucinproducing cells, the increase in the number of acid mucin-producing cells in the T3 group suggested that acidic mucins are more soluble than neutral mucins in good environmental conditions. 53 In fish of the T3, a greater quantity of fluid mucus covered the branchiae compared to that of other animals in the control group and other treatment groups.…”

“…Low viscosity protects and lubricates the branchial epithelium against friction. 51 Exposure to pollutants may affect the propagation of mucosal cells with different types of mucus-substances that are found in fish as a result of their exposure to stress agents. 52 Research on the population density of mucosal cells from the branchial epithelium of Nile tilapia showed that other factors (aside from the physical and chemical properties under analysis), such as parasites and toxic agents in the sediments, may affect the number of mucosal cells in the findings described above.…”

“…54 The proliferation and hypersecretion of mucosal cells in the branchiae are a defence mechanism for chronic stress response and may jeopardise the branchial function based on the severity of the process within the context of stress situations. Furthermore, 51 reported that the proliferation of mucosal cells with different types of mucus-substances protected the branchial epithelium from contaminants and pathogenic agents and aided in osmo-regulation. However, large quantities of mucus secretion, especially of neutral mucus, may be more harmful and make gas exchange more difficult.…”

Influência da densidade de estocagem no desempenho produtivo do acará-bandeira (Pterophyllum scalare) cultivado em gaiolas

“…Embora a densidade de estocagem possa alterar o crescimento dos peixes, principalmente em relação à competição por espaço, alimento e oxigênio (ReiS et al, 2009), em experimentos realizados com Tricogaster (Trichogaster trichopterus) com densidades de estocagem de (0,05; 0,10 e 0,15 peixes/L), não se observaram diferenças significativas na concentração de oxigênio dissolvido (ZuAnon et al, 2004).…”