Topological and histological descriptions of the preoptic area and hypothalamus of the cardinal tetra Paracheirodon axelrodi were performed. Standard histological paraffin sections were used and stained with Nissl technique, and plastic sections for high-resolution optic microscopy (HROM). The preoptic area showed some differences related to the location of the magnocellular preoptic nucleus (PM) and the size of the neurons in this region, as they were the biggest in all the preoptic area. Additionally, within the preoptic area, the different structures that comprise the organum vasculosum of the lamina terminalis (OVLT) were identified and characterized. The hypothalamus could be subdivided in three regions -the ventral, the dorsal and the caudal hypothalamic regions -neuron morphology, size and staining pattern were similar in all of them.Keywords: Brain, High resolution optic microscopy (HROM), Organum vasculosum of the lamina terminalis (OVLT).Se realizó la descripción topológica e histológica del área preóptica e hipotálamo en el Neón cardenal Paracheirodon axelrodi. Se usaron cortes obtenidos con tecnicas histológicas estándar, coloreados con técnica de Nissl y secciones en resina con microscopía óptica de alta resolución (MOAR). El área preóptica muestra algunas diferencias relacionadas con la localización del núcleo preóptico magnocelular (PM) y el tamaño de algunas neuronas en esta región, puesto que estas eran las más grandes de toda el área preoptica. Adicionalmente, dentro del área preóptica, fue posible identificar y caracterizar las diferentes estructuras que componen el órgano vasculoso de la lámina media (OVLM). El hipotálamo puede sudividirse en tres zonas: la zona hipotalámica ventral, la zona hipotalámica dorsal y la zona hipotalámica caudal. La morfología de las neuronas de los núcleos que comprenden las diferentes zonas del hipotálamo tiene tamaño, forma y coloración similar.Palabras Clave: Cerebro, Microscopía óptica de alta resolucion (MOAR), Órgano vasculoso de la lámina terminal (OVLT).
Histology and morphometry of the eye in the freshwater Paracheirodon axelrodi (Characiformes: Characidae). The visual system of Teleost fishes has a wide range of adaptations. The eye has suffered modifications, mainly towards better sensitivity and visual resolution according to specific environmental conditions. In that way, this organ is so important for survival. In spite of being the most commercialized Orinoquía species, and one of the most important ornamental fish worldwide, there are almost no studies on the communication systems of P. axelrodi (including vision). We studied the eye in ten individuals of P. axelrodi, with a mean total length of 2.7 cm (SD= 0.2, n= 20). We measured eye relative size (TRO) after sacrifice. Heads were processed for hematoxylin-eosin, and 8 µm thick sections were obtained. Images were digitalized for histological identification and morphometrics. The relation between TRO and body length was 9.8% (SD= 1.1, n= 20); lens was spherical with a relative size of 64.3% (SD= 4.9, n= 20). Rete mirabilis choroid was composed mainly by capillaries, while sclera was composed of cartilaginous tissue. Retina with eight layers and two membranes. An areae centrales was observed in the posterior retina. Iris covered by a simple cubic epithelium. Cornea of endotelial tissue with two membranes. Pupil almost circular, with a naso-caudal elongation. Measures of retina thickness were as follows:
Desde una analítica de la racionalidad neoliberal y considerando la marcada narrativa progresista que presupone la explotación de recursos ambientales como forma de desarrollo para las regiones, abordamos la amalgama Estado-empresa en el marco de las economías neoliberales, en relación con el fenómeno de la minería. Con este propósito, presentamos los hallazgos de un estudio llevado a cabo en un municipio del departamento de Caldas-Colombia, basado metodológicamente en el interaccionismo simbólico y en el que participaron mineros de hecho y otros que trabajaban para la empresa minera. A partir de los relatos, concluimos que la minería a gran escala, aunque ha representado posibilidades laborales formales, no solo ha implicado impactos ambientales y dislocado formas de producción local. El encumbramiento neoliberal de la figura de la empresa y la articulación Estado-empresa configurada en su seno, han precarizado la labor minera y los modos de vida con arraigo en la tradicionalidad.
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