RESUMO
Minipigs, 2, 4, 6 months old, were used to evaluate the relationship between myelination in the fiber tracts of the central nervous system (CNS) of this animal during development. Histological results showed an increased density of the myelinated fibers as well as branching of these fibers in the areas studied, including the cortical white matter, olfactory tract, the corticospinal tract, the fasciculus cuneatus and the spinal V nucleus from 2 to 6 months old. By 6 months, the pig was sexually matured. Concomitantly, there was an increase in high signal-intensity regions (sites) in the magnetic resonance T(1)-weighted images as myelination progressed. There is a good correlation between the histologically observed progress of myelination and the T(1)-weighted images in the development of the CNS of the pig.
Assuntos
Encéfalo/crescimento & desenvolvimento , Imageamento por Ressonância Magnética , Fibras Nervosas Mielinizadas/metabolismo , Fatores Etários , Animais , Animais Recém-Nascidos , Encéfalo/anatomia & histologia , Encéfalo/citologia , Feminino , Processamento de Imagem Assistida por Computador/métodos , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/metabolismo , Coloração e Rotulagem/métodos , SuínosRESUMO
Scanning retinal electronmicroscopy studies demonstrated the presence of both twin cones (two identical cones adhered together) and double cones (two non-identical cones adhered together) in the retinae of the major forms of fish, which included actinopterygi, elasmobranch, and teleosts. The complexity of these visual cells in the retinae of different groups of fishes was revealed for the first time and reflected on the diversities of functions of the fish retina in general.
