Localization of parabrachial nucleus neurons projecting to the thalamus or the amygdala in the cat using horseradish peroxidase.

Topographical localization of parabrachial nucleus (PBN) neurons projecting directly to the thalamus or the amygdala was examined in the cat by the horseradish peroxidase (HRP) method. After HRP injection in the central nucleus of the amygdala, PBN neurons labeled with the enzyme were seen ipsilaterally in the ventral portion of the lateral PBN as well as in the medial PBN. When the HRP injections were centered on the parvocellular portion of the posteromedial ventral nucleus of the thalamus (VPMpc), HRP-labeled neurons were observed ipsilaterally in the dorsal portion of the lateral PBN as well as in the medial PBN. Within the medial PBN, the distribution of neurons projecting to the amygdala overlapped that of neurons projecting to VPMpc; the cell bodies of the former neurons, however, tended to be more elongated than the latter, and the mean of the average soma diameters of the former was significantly larger than the latter. On the other hand, in the lateral PBN no significant differences were noted between the means of the average soma diameters of neurons projecting to VPMpc and those projecting to the amygdala. The PBN neurons in the cat were presumed to transmit gustatory and general visceral information ipsilaterally to the thalamic taste region and the limbic areas in the basal forebrain.     

The histochemistry of the spiral prominence

Summary In order to demonstrate the existence of oxidative enzymes, lysosomal enzymes, adenosine triphosphatase, butyrylcholinesterase, esterases and alkaline phosphatase, the spiral prominence and the neighbouring tissues of the guinea pig were studied histochemically. The results were discussed in connection with the function of the spiral prominence. Morphological features and enzymatic activities suggested that the spiral prominence serves as a balance between the perilymph and the endolymph, which are both absorptive and secretory and are depending on chemical and physical conditions.

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Zusammenfassung Die Prominentia spiralis and das umgebende Gewebe werden histochemisch untersucht, um die oxydativen and lysosomalen Fermente, die ATPase, die Butyrylcholinesterase, unspezifische Esterasen und alkalische Phosphatase nachzuweisen. Die Ergebnisse werden in Zusammenhang mit der Funktion der Prominentia spiralis diskutiert.Die morphologischen Eigenschaften und die Enzymaktivitäten deuten darauf hin, daß die Prominentia spiralis dem Ausgleich zwischen Perilymphe und Endolymphe dient und zwar sowohl absorbierend wie such sezernierend, abhängig von den chemischen and physikalischen Bedingungen.