21,826 research outputs found
The tertiary gustatory center in sunfishes is not nucleus glomerulosus
Injection of horseradish peroxidase into the secondary gustatory nucleus of the green sunfish, Lepomis cyanellus, resulted in retrogradely filled neurons bilaterally in the viscerosensory column of the brainstem and in anterograde transport revealing ipsilateral terminal fields in the preglomerular tertiary gustatory nucleus, the nucleus of the torus lateralis and the central and periventricular nucleus of the inferior lobe. Thus, the glomerular nucleus of percomorph teleosts is not a tertiary gustatory center. It is proposed that the term ânucleus glomerulosusâ be reserved for the nucleus involved with vision and that the preglomerular subdivision involved in gustation be termed ânucleus gustatorius tertiusâ
An Evolutionary Interpretation of Teleostean Forebrain Anatomy
During the past few years, our investigations of the forebrain in the zebrafish (a teleost fish) have shown that its molecular anatomy and expression patterns of genes involved in the regulation of neuronal transmitter phenotypes, such as gamma-aminobutyric acid- (GABA-)ergic neurons, are very similar to those seen in mammalian model organisms such as mouse and rat. For example, we have been able to identify previously undiscovered homologies, such as subpallial regions in the zebrafish that are homologous to the medial and lateral ganglionic eminences in mammals, as well as regions homologous to the larval eminentia thalami and its adult derivative, the bed nucleus of the stria medullaris. Furthermore, in what we term the partial eversion model of the telencephalon in teleosts, we propose homologies to all four mammalian pallial areas and conclude that the posterior zone of the dorsal telencephalic area in teleosts is homologous to the piriform cortex and is formed by a migratory stream of cells originating in a dorsomedial zone of the pallium (the primordial medial zone of area dorsalis telencephali). In this review we critically discuss and justify these findings in the context of forebrain evolution in fishes. Copyright (C) 2009 S. Karger AG, Base
Descending telencephalic information reaches longitudinal torus and cerebellum via the dorsal preglomerular nucleus in the teleost fish, Pantodon buchholzi
The Impact of Customs Procedures on Business Performance: Evidence from Kosovo
This paper aims to identify formal and informal institutional factors in customs procedures and their impact on the performance of small and medium-sized enterprises (SMEs) involved in international trade in Kosovo based on a questionnaire conducted in 2009. The econometric findings show that one of the most important obstacles encountered by SMEs are regular appeals against customs decisions that are assumed to be inter alia a consequence of frequent changes in over-complicated laws and regulations. However, there is a positive and significant effect of the formal customs institutions that facilitate the trade of imported goods, namely of so-called customs procedures with economic impact.customs, firm performance, formal and informal institutions, small and medium-sized enterprises, Kosovo
Possible multiple evolution of indirect telencephalo-cerebellar pathways in teleosts: studies in Carassius auratus and Pantodon buchholzi
Among vertebrates, telencephalo-pontine systems exist only in birds and mammals. However, three nuclei in the diencephalon and mesencephalon of teleost fishes have been indicated â analogous to the pons â to represent relay stations between telencephalon and cerebellum. Since two of these nuclei (dorsal preglomerular nucleus, dorsal tegmental nucleus) have only been described in the highly derived, electrosensory mormyrids, we investigated telencephalic connections in two nonelectrosensory teleosts, the goldfish Carassius auratus and the freshwater butterflyfish Pantodon buchholzi, and cerebellar connections only in the latter species, since for C. auratus these connections are already established. Horseradish peroxidase tracing reveals that C. auratus has a dorsal tegmental nucleus and a paracommissural nucleus both of which are telencephalo-recipient and project to the cerebellum, and that P. buchholzi has a dorsal preglomerular nucleus with such connections. These results extend our knowlegde of the distribution and, therefore, the phylogeny of telencephalo-cerebellar systems in teleosts. Similar to tetrapods, teleosts appear to have developed telencephalo-cerebellar systems several times independently
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