The nonpyramidal neurons in area 17 of cat visual cortex have been examined in Golgi preparations. From their dendritic patterns, neurons are classified as being multipolar, bitufted, or bipolar, and on the basis of the abundance of dendritic spines as spinous, sparsely spinous, or smooth. When neurons are so classified seven different types of nonpyramidal neurons are encountered in layers I1 through V.Three of the types of multipolar neurons in layers I1 through V have spherical dendritic trees. The small multipolar cells have smooth dendrites and are the smallest neurons in the cortex. They have short dendrites and dense local axonal plexuses and occur throughout layers I1 to V. The sparsely spinous stellate cells have longer dendrites, are confined to layer II/III, and have local axonal arborizations, whereas the spinous stellate cells are limited to layer IV. A fourth type of multipolar neuron in layers I1 through V is the basket cell. Such neurons have elongate dendritic trees and either smooth or sparsely spinous dendrites. Depending upon the orientation of the neurons in the sections, their axons appear to form arcades or long, horizontally extended branches, or a mixture of these two axonal patterns. The terminal portions of the axons of these basket cells pass around the cell bodies of adjacent neurons.The two types of bitufted neurons in layers I1 through V have vertically oriented dendritic trees. One type, the chandelier cell, has smooth dendrites and a characteristic axon forming vertical strings of terminals. The other sparsely spinous bitufted neurons have axons producing vertically oriented plexuses. The remaining type of neuron encountered in layers I1 through V is a bipolar cell. The bipolar cell has a single major dendritic trunk arising from each pole of the cell body, and each of these gives rise to a very narrow, long, and vertically oriented dendritic tree. The axon usually takes origin from one of the primary dendrites.In layer I are horizontally oriented, bitufted cells with smooth dendrites. The s o n s of these horizontal cells of layer Z arise from one of the primary dendritic trunks and appear to form a plexus confined to layer I. Horizontally oriented neurons are also present in deep layer VI, but the horizontal cells of layer VZ are bipolar. The other two neuronal types in layer VI are multipolar cells with sparsely spinous dendrites. The larger of these two types resembles the basket cells in layers I1 through V, the only important difference between them being that in addition to the long horizontal branches, the axons of the basket cells of layer VZ have a long ascending branch which reaches at least as far as layer 1V. The other sparsely spinous cells of layer VZ are medium sized. Their axons take a descending and oblique course before elaborating a locally distributed plexus.The various types of neurons defined in this study are compared with neurons described by previous authors who have examined the populations of nonpyramidal cells in area 17 of cat visual cortex an...

Different fluorescent tracers were applied to the surface of the cortex of rats, marmosets and one hedgehog. Irrespective of the kind of tracer and the depth of penetration, some perikarya of layer VI were labelled in each specimen and in all cortical regions. In the rat almost all labelled neurons were packed in sublayer VIb, in the marmoset such cells were dispersed throughout layer VI, whereas in the hedgehog the degree of their segregation to sublayer VIb was intermediate. Additional experiments in the rat indicated that most of the medium-sized neurons in the VIb layer project to layer I, that most of the perikarya projecting to the thalamus are localized in sublayer VIa, that different neurons project to the thalamus and to the surface of the cortex, and that only very few perikarya in deep parts of layers III and V and of sublayer VIa send axons or axon collaterals to layers I and II.

The concept of nutritional programming raises the interesting possibility of directing specific metabolic pathways or functions in juvenile fish, for example, to improve the use of substitutes to fishmeal and oil, and hence to promote sustainability in aquaculture. The aim of the study was to determine effects of early nutritional stimuli of gilthead seabream larvae and check if nutritional programming of gilthead sea bream is possible between 16 days post hatching (dph) and 26 dph. A trial was conducted to determine the effects of early nutritional stimuli of gilthead seabream larvae. Five experimental microdiets (pellet size <250 lm) were formulated containing five different proportions of a marine lipid source rich in long-chain polyunsaturated fatty acids (LC-PUFA) and two vegetable lipid sources rich in linolenic and linoleic acids. The results of this study demonstrate that dietary n-3 LC-PUFA levels increased larval growth and survival affecting D6 desaturase gen (fads2) expression and retinal neurons density. However, the high mortalities obtained along ongrowing in fish fed low n-3 LC-PUFA at 16 dph constrained the feasibility of nutritional programming of gilthead seabream during this late developmental window and needs to be further investigated.

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Architectural characteristics of the thalamus in echidnas and rats were compared in sections stained to reveal cell bodies, myelin, acetylcholinesterase, succinate dehydrogenase and cytochrome oxidase. Numerous species differences were noticed: in general, the thalamus is architecturally more homogeneous in echidnas than in rats, especially anteriorly. In this report we emphasize the presence of a relatively large structure localized in the anteromediodorsal part of the thalamus in echidnas. This structure, previously shown to project to the frontal cortex, contains very small amounts of acetylcholinesterase and the oxidative enzymes; in this respect it resembles the mediodorsal nucleus of rats. The same properties make this formation different from the anterodorsal and anteroventral nuclei in rats, the equivalents of which could not be identified in echidnas. The anteromediodorsal region of the thalamus in echidnas consists chiefly of two cytoarchitecturally different regions: the medial, 'polymorphic' part contains relatively small, densely packed, multiform perikarya, whereas the lateral, 'monomorphic' part is characterised by larger, sparse neurons with little cytoplasm and round, large, empty-looking nuclei in which the nucleolus is clearly seen. We conclude tentatively that this brain structure of echidnas corresponds to the mediodorsal nucleus in placental species. Further studies of connections and chemical properties will be essential to determine the degree of correspondence of the presumed 'frontal lobe system' in echidnas to that in other mammals.