ABSTRACT
The objective of this study was to characterize macroscopically and microscopically the liver of the collared lizard Tropidurus torquatus, using two adult females and two adult males, captured on the banks of Marambaia Isle in Sepetiba Bay in the state of Rio de Janeiro. Fragments of liver were fixed in Bouins liquid and submitted to routine histological techniques. Sections were cut by a rotary microtome to 5 mm thickness and stained by with HE, PAS, Gomori Trichrome and Gomoris reticulin impregnation. The liver this lizard is a large, speckled dark brown organ composed of a right and left lobe. The gallbladder is located on the visceral surface of the right lobe. The lobules are polyhedral in shape and separated by a thin layer of interlobular connective tissue, forming trabeculae. These contain bile ducts, branches of portal vein and of hepatic artery. The hepatocytes are also polyhedric and have varied sizes. The majority of these cells have nuclei offset toward the periphery, and the cytoplasm is highly vacuolated and was not well evidenced by the histological techniques utilized. The hepatic parenchyma is supported by delicate reticular fibers surrounding hepatocytes and sinusoids. Large quantities of melano-macrophage centers are present in the parenchyma.
Subject(s)
Animals , Male , Female , Adult , Liver/anatomy & histology , Liver/physiology , Liver/blood supply , Lizards , Microscopy , X-Ray MicrotomographyABSTRACT
Micro- and mesozooplankton were studied in the Sergipe estuary, northeastern Brazil, in order to assess the temporal variability in abundance and biodiversity under stressed conditions (urban pollution). Zooplankton samples and abiotic data were collected at one station during a full tidal cycle in July 2001 and in February 2002, corresponding to the rainy and dry seasons, respectively. The salinity regime was euhaline-polyhaline. Phosphate and dissolved oxygen were higher in July 2001, and nitrite, nitrate and ammonia in February 2002. Chlorophyll-a concentrations were low as a result of light limitation, with 1.18 ± 0.88 µg.m-3 in February and 1.53 ± 1.48 µg.m-3 in July. Fifty-nine zooplankton taxa were identified. Microzooplankton were abundant, mainly the tintinnid Favella ehrenbergii, and ranged from 18,649 ind.m-3 in July to 678,009 ind.m-3 in February. Mesozooplankton ranged from 1,537 ind.m-3 in July to 37,062 ind.m-3 in February and were dominated by barnacle nauplii in July and by copepods in February. The cluster analysis by taxa revealed the existence of three distinct groups: resilient species, characteristic of estuarine areas and occurring during all the year; species mainly more abundant in July (indicators of a healthier environmental condition); and species more abundant in February (tolerant to poor water quality).
O micro-e o mesozooplâncton foram estudados no estuário do rio Sergipe, Nordeste do Brasil para conhecer a variação temporal em abundância e biodiversidade sob condições de estresse. Amostras do zooplâncton e dados abióticos foram coletados em uma estação durante um ciclo completo de marés em julho de 2001 e em fevereiro de 2002, correspondendo aos períodos chuvoso e seco, respectivamente. O regime de salinidade variou de euhalino a polihalino. O fosfato e o oxigênio dissolvidos foram mais elevados em julho 2001, e o nitrito, o nitrato e a amônia, em fevereiro 2002. As concentrações de clorofila-a foram baixas devido à limitação da luz, com valores médios de 1,18 ± 0,88 µg.m-3 em fevereiro e 1,53 ± 1,48 µg.m-3 em julho. Foram identificados 59 taxa zooplanctônicos. O microzooplâncton foi abundante, principalmente o tintinídeo Favella ehrenbergii, que variou de 18.649 ind.m-3 em julho a 678.009 ind.m-3 em fevereiro. O mesozooplâncton variou de 1.537 ind.m-3 em julho a 37.062 ind.m-3 em fevereiro e foi dominado por náuplios de Cirripedia em julho e por Copepoda em fevereiro. A análise de agrupamento por taxa revelou a existência de três grupos: espécies resilientes, características de áreas estuarinas de ocorrência contínua; espécies que dominaram em julho (indicadores de uma melhor condição ambiental); e espécies mais abundantes em fevereiro (tolerantes à baixa qualidade da água).