The Origin of a New Progenitor Stem Cell Group in Human Development.

The observation of two precursor groups of the early stem cells (Groups I and II) leads to the realization that a first amount of fetal stem cells (Group I) migrate from the AMG (Aortal-Mesonephric-Gonadal)-region into the aorta and its branching vessels. A second group (Group II) gains quite a new significance during human development. This group presents a specific developmental step which is found only in the human. This continuation of the early development along a different way indicates a general alteration of the stem cell biology. This changed process in the stem cell scene dominates the further development of the human stem cells. It remains unclear where this phylogenetic step first appears. By far not all advanced mammals show this second group of stem cells and their axonal migration. Essentially only primates seem to be involved in this special development.

Vagal paraganglia of the rat.

Paraganglia are associated with every branch of the rat vagus nerve except the pharyngeal branch. Some of the paraganglia closely resemble the glomus caroticum, whereas others appear like small, intensely fluorescent (SIF) cells of autonomic ganglia. The paraganglionic cells of SIF cell-like bodies (SLB) store catecholamines (the most abundant is probably noradrenaline) and in some cases neurotensin. The innervation pattern of SLB is variable and their physiological role remains unclear. Paraganglionic cells of glomus-like bodies (GLB) predominantly store dopamine and probably also to a lesser extent noradrenaline. These putative chemoreceptor organs receive sensory innervation from nodose ganglion neurons as revealed by degeneration experiments and by anterograde neuronal tracing. Substance P- and calcitonin gene-related peptide-immunoreactive fibres seen in the region of vascular entry into the GLB may account for some of these sensory fibres, but the peptide/classical transmitter stored in sensory terminals synapsing on paraganglionic cells is unknown. Ultrastructural immunocytochemistry revealed vasoactive intestinal polypeptide (VIP)-immunoreactive fibres lying in the interstitial space between paraganglionic cells and large capillaries. These fibres may originate from VIP-immunoreactive neurons, being frequently attached to GLB. The major difference between GLB and the glomus caroticum concerns their blood supply and related innervation: Arteries and arterioles do not penetrate into GLB and, accordingly, noradrenaline- and neuropeptide Y-containing nerve fibres are lacking within GLB. This peculiar arrangement of paraganglionic parenchyma and arterial blood supply may be one of the reasons for the different physiological properties of vagal and carotid arterial chemoreceptors.

Histomorphometric and morphologic studies of the carotid body and aortic paragangliomas.

Morphometric and morphological parameters have been evaluated in tumours of carotid body paraganglia and of aorticopulmonary and aorticosympathetic paraganglia. Paragangliomas are characterized by a higher cell density and rounder nuclei (roundness factor) than non-neoplastic carotid body paraganglia. The nuclear area has similar mean values in tumours and normal paraganglia; however, the former group shows higher standard deviation values and coefficients of variation, reflecting the fact that paragangliomas have nuclei of variable size; the variation is more pronounced in aorticopulmonary and aortico-sympathetic paragangliomas. However, subgroups on the basis of morphological features (architectural patterns and degree of intensity of argyrophilia), site of origin, and clinical behaviour (metastases and recurrences) show no morphometric differences.

Paragânglios intraganglionares em coraçöes humanos adultos / Intraganglionic paraganglia in adult human hearts

Descrevem-se dois paragânglios intraganglionares observados em coraçöes de homens adultos, aparentemente sadios, que tiveram morte violenta. Os paragânglios assim localizados poderiam relacionar-se ao controle da funçäo ganglionar

Paraganglia of the bladder.

Normal paraganglia containing high amounts of catecholamines are a constant feature of the wall of the bladder in elderly men. The paraganglia in this location might give rise to pheochromocytomas. The importance of the local endocrine effects in the regulation of the muscular tone in the bladder is discussed.