Endocrine disruption by cadmium: Mechanisms and effects on the reproductive axis and stress response in rainbow trout, oncorhynchus mykiss

The purpose of this research was to investigate the sub-chronic effects of environmentally realistic cadmium (Cd) concentrations on the reproductive and developmental axes and stress response of rainbow trout with the intention of furthering our understanding on the endocrine-disrupting mechanism(s) of action of this metal in teleosts. This study showed for the first time that very low Cd concentrations (0.05, 0.25, 0.50 and 2.50 pg/L) can result in a multifaceted toxicity paradigm, with important effects on the reproductive axis, and to a lesser extent on the stress response of rainbow trout. Cd exposure has impaired three life-stages of trout: eggs, larvae and juveniles with juvenile being the most sensitive stage examined. The lowest concentrations used caused premature hatching and the highest caused delayed hatching. Interestingly final hatching success was not affected. 2.50 pg/L Cd negatively affected larval growth: larvae were shorter in length and weighed less compared to controls. Plasma sex steroid concentrations were increased in juveniles at all Cd concentrations after 28 days. The specific toxic site(s) of action of Cd on steroidogenesis was determined using an in vitro testicular cell preparation. Our results indicate that there are both stimulatory and inhibitory sites near the pituitary hormone receptor location, on the first steps of the pathway. Similarly, the hypothalamus-pituitary-interrenals axis and stress response were both affected by Cd. Decreased plasma cortisol concentrations were observed at all concentrations from 7 to 40 days of exposure but they were not accompanied by interrenal impairment or alterations in other stress response parameters. However, interrenal steroidogenesis was impaired in a dose-dependent manner in vitro. One major inhibitory site(s) of action of Cd on the cortisol synthesis pathway is located after the pituitary hormone receptor location and prior to the cholesterol cleavage. Negative effects of Cd at concentrations as low as 0.05 pg/L have never been reported in the literature. Since the guidelines for Cd are under review by the British Columbia Ministry of Environment, our results may add important data in determining new guideline values

Diagnóstico da idade fetal humana baseado no desenvolvimento normal do rim

Introdução e objetivos: O diagnóstico da idade fetal humana é usualmente estimado com base em medidas de tamanho e peso do feto. No entanto, esta estimativa não é totalmente acurada, e muitas vezes é necessário combinar outros dados para determinar a idade fetal. A análise do desenvolvimento embriológico normal do rim pode auxiliar nesta determinação. A histologia deste processo, apesar de bem descrita, apresenta uma documentação fotográfica escassa. Pretende-se preencher esta lacuna fornecendo a histologistas e patologistas, especialmente aos inexperientes, informações sobre o desenvolvimento renal no período pré-natal através de microfotografias. O objetivo do presente estudo foi conceder maior acurácia ao diagnóstico da idade fetal humana através da classificação proposta e da documentação apresentada. Material e métodos: Necropsias de fetos humanos de 6 a 40 semanas de gestação foram estudadas através de microscopia óptica. O tecido renal foi analisado segundo a ocorrência de glomérulos e túbulos rudimentares, em diferenciação e maduros; distribuição espacial dos glomérulos no parênquima; presença de tecido nefrogênico; e diferenciação corticomedular. Foram analisados no mínimo cinco exames diferentes para cada semana de desenvolvimento, perfazendo um total de 204 exames. As características foram quantificadas e o processo documentado através de microfotografias. Resultados e considerações finais: O desenvolvimento fetal do rim humano foi dividido em oito estágios com base nas características histológicas e a quantificação realizada. Os estágios foram documentados através de microfotografias. A neoformação de néfrons ocorreu até a 34ª semana. A partir da 35ª semana, os túbulos e glomérulos continuam a amadurecer, não ocorrendo, no entanto, a formação de novos néfrons. A classificação proposta pretende conceder maior acurácia ao diagnóstico da idade fetal humana.Background and aims: The diagnosis of human fetal age is usually estimated based on the measurement of crown-rump length or crown-heel length and the weight of the fetus. However, this estimate is not totally accurate and sometimes is necessary to combine other data to determine the fetal age. An analysis of the normal embryological development of the kidney may assist in this determination. The histology of this process, although well described, lacks photographic documentation. We intend to fill this gap by providing histologists and pathologists, especially inexperienced ones, with information about the staging of the renal development through microphotography. The objective of the present study was to achieve greater accuracy for the diagnosis of human fetal age through the proposed classification and the photographic documentation presented. Material and methods: Normal embryological development of the human kidney was studied by light microscopy. The fetal period from 6 to 40 weeks of gestation was observed according the stage of maturity of glomeruli and tubules; localization of glomeruli, occurrence of nephrogenic tissue and cortico-medullary differentiation. At least 5 different exams were observed from each week of development. Two hundred four exams were analyzed in the whole study. The histological characteristics were quantified and the process was documented by microphotography. Results and final considerations: The fetal development of the kidney was divided into 8 stages, which was documented through microphotography. Nephron structural formation occurred until the 34th week of prenatal development. From the 35th week on, tubules and glomeruli continued to mature without the formation of new nephrons. The proposed classification intends to improve the accuracy of the fetal age diagnosis

Estudo morfológico do desenvolvimento embrionário de espécies de Aegla (crustacea, decapoda, aeglidae)

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Estudo morfológico do desenvolvimento embrionário de espécies de Aegla (crustacea, decapoda, aeglidae)

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Desenvolvimento embriológico de Aegla sp. : resultados preliminares

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Desenvolvimento embriológico de Aegla sp. : resultados preliminares

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Morfologia do aparelho reprodutor de Aegla platensis (Crustacea, Anomura, Aeglidae)

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Morfologia do aparelho reprodutor de Aegla platensis (Crustacea, Anomura, Aeglidae)

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