Neural Inputs to the Subcommissural Organ
Among the circumventricular organs of the vertebrates, the subcommissural organ (SCO), a specialized area of ependyma, is one of the most fascinating. Its modified ependymal cells arranged in a pseudostratified epithelium are elongated, high cylinders that contact apically the ventricular cerebrospinal fluid. The SCO ependymocytes appear as specialized glial cells displaying some cytochemical characteristics that differentiate them from other types of glial cells (Didier et al. 1986; Chouaf et al. 1989). In all vertebrates, the SCO is easy to recognize, but despite its constant morphology, this organ, which differentiates very early during embryonic life, shows conspicuous specific variations especially in the innervation of its ependymal and hypendymal elements. Thus, a few species of higher vertebrates possess a dense innervation of the SCO while most species are totally devoid of such innervation. The axoglandular innervation of the SCO is richest and most differentiated in the rat. Hence, the rat SCO provides a classical model for studying certain aspects of neuron—glia interactions.
KeywordsSerotonin Glutamine Tryptophan Adrenaline Vasopressin
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