Tributyltin (TBT) toxicity: Effects on enteric neuronal plasticity and intestinal barrier of rats' duodenum.

Tributyltin (TBT) is a biocide used in the formulation of antifouling paints and it is highly harmful. Despite the ban, the compound persists in the environment, contaminating marine foodstuffs and household products. Therefore, considering the route of exposure to the contaminant, the gastrointestinal tract (GIT) acts as an important barrier against harmful substances and is a potential biomarker for understanding the consequences of these agents. This work aimed to evaluate histological and neuronal alterations in the duodenum of male Wistar rats that received 20 ng/g TBT and 600 ng/g via gavage for 30 consecutive days. After the experimental period, the animals were euthanized, and the duodenum was intended for neuronal histochemistry (total and metabolically active populations) and histological routine (morphometry and histopathology). The results showed more severe changes in neuronal density and intestinal morphometry in rats exposed to 20 ng/g, such as total neuronal density decrease and reduction of intestinal layers. In rats exposed to 600 ng/g of TBT, it was possible to observe only an increase in intraepithelial lymphocytes. We conclude that TBT can be more harmful to intestinal homeostasis when consumed in lower concentrations.

Ultrastructure of dermal denticles in sharpnose shark (Rhizoprionodon lalandii) (Elasmobranchii, Carcharhinidae).

The presence of denticles in the external surface, oral cavity, fins, and clasper of Elasmobranchii has been widely reported. These structures, called body denticles, may be observed on the body surface of sharks. Dermal and oral denticles are made up by a basal plate that is embedded in the dermis, forming a peduncle that grows from the base to the crown. These denticles may protect the skin against abrasion, and improve hydrodynamics and gill arches function. Rhizoprionodon lalandii is a widely distributed and very common species in Brazilian coastal areas. The aims of this study was to compare the morphology of oral and body denticles of R. lalandii to understand the implications of these structures in the behavior of these animals. Morphological analysis showed that there are differences between dermal and oral denticles, which are related to their role in different body regions. Body denticles have three cusps, and well-defined crests and ridges, and literature data suggest that suggest that hydrodynamics is their main function. Most of the oral denticles have only one cusp, and their morphology and distribution showed that their main functions are preparing food to be swallowed and protecting the oral cavity against abrasion.

Alterations in the duodenum myenteric neurons of Wistar ratsafter ingesting of 2, 4 dichlorophenoxyacetic acid

The 2,4 dichlorophenoxyacetic acid (2,4-D) is a systemic herbicide whose effects in animal organic systemshave been examined in previous studies, being the neurotoxicity considered the predominant effect. However,the studies that detect the 2,4-D neurotoxicity have merely focused in the central nervous system, andtherefore, little is known about the effect of this herbicide in the enteric nervous system. This study aimedto verifying the 2,4-D effects on the myenteric neurons in duodenum of Wistar rats. Ten 60-day-old maleWistar rats (Rattus norvegicus) were divided in two groups: control group (C) that did not receive 2,4-D andexperimental group (E) that received 5.0 mg of 2,4-D/kg for 15 days. At the end of experimental period, theanimal were euthanized, the duodenum was collected and processed for NADPH-diaphorase histochemicalanalysis in order to expose the nitrergic myenteric neurons (NADPH-dp). In the light microscopy analysis, thewhole-mount preparation obtained from duodenum of each animal were image-captured in 120 and 40 fields,for quantitative and morphometric analyses of myenteric neurons, respectively. The neuronal density was notaffected when comparing the two groups, but an increase (p > 0.05) of 8.5% was observed in the cell bodyarea of neurons in the E group. In conclusion, the ingestion of 2,4-D at a dosage of 5.0 mg/kg body weightfor 15 days does not change the neuronal density, but promotes the hypertrophy of NADPH-dp myentericneurons in duodenum of the rats of this study.

Gross and microscopic observations on the lingual structure of the Franciscana (Pontoporia blainvillei--Gervais and d'Orbigny, 1844).

In most anatomical studies developed with mammals, the tongue is described as highly differentiated among different species. However, studies on the tongue of aquatic mammals are still limited as compared to those on terrestrial mammals. The aim of this study was to describe the tongue morphology of the Franciscana dolphin (Pontoporia blainvillei) using macroscopic observations, light, and scanning electron microscopy. Microscopically, the dorsal surface was covered by a keratinized stratified epithelium. Salivary gland acini were found on the middle and caudal third of the tongue. The dorsal surface was totally covered by filiform papillae with a connective tissue core and a connective tissue structure round in shape in the middle and caudal regions.