Many studies have reported on the different types of placenta in different species, but accessory or paraplacental structures are mentioned only in species that have such a nutrient-exchanging mechanism. Hystricomorph rodents possess a subplacenta, swine and equines have the placental areola, equines have the chorionic girdle, and carnivores have hemophagous organs that are equivalent to the placental hematoma in ruminants. These accessory structures are specialized tissues for specific nutrient exchanges in different species, and they are adaptive modifications exhibited by domestic and wild species to remedy the nutritional deficiencies that are related to permeability of the main placenta to important nutrients for the growth and development of the fetus during the gestation.
O reconhecimento materno da gestação é o período em que o concepto sinaliza a sua presença para a mãe. Esse é um importante momento da gestação, que pode ser decisivo para o progresso da prenhez. Durante a gestação, ocorre uma série de eventos hormonais, envolvendo progesterona e prostaglandinas, sendo fundamental a função do corpo lúteo, uma glândula temporária formada a partir da ovulação de um folículo. O corpo lúteo produz a progesterona, esteroide envolvido tanto na ciclicidade ovariana quanto no estabelecimento e manutenção da gestação, na maioria dos mamíferos. Algumas particularidades dos eventos envolvidos na relação materno-fetal durante o reconhecimento da gestação em espécies domésticas foram abordadas nesta revisão; entre estas, foi descrito o papel fundamental da proteína interferon-tau (INF-T) com ação antiluteolítica comprovada e que está associada ao reconhecimento materno da gestação em ruminantes; a movimentação do embrião equino, mantendo a sua sinalização; os estrogênios produzidos pelos conceptos suínos com função luteotrófica para a espécie, mas que também possui função luteolítica em outras espécies.
In the context of the American Revolution, alongside the influential notion of constituent power advocated, for instance, by the Federalists, emerged an alternative and potent perspective about this concept. This perspective, which was particularly strong in revolutionary Pennsylvania, had at least two distinctive features. First, rather than limiting constituent power to a sort of ante-room of constitutional authority, this view conferred primacy to the constituent process over the institutional machinery. Second, instead of exclusively assigning the exercise of constituent power to a few specialists, this perspective invented ways for the multitude to exercise its power directly. This article examines this particular vision of constituent power. This investigation, as I argue, can both assist in demystifying some common assumptions entrenched in the concept of constituent power and provide insights for contemporary reflection on the limits of representative democracy.
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