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Biomedical subjects

H Petter

Publications and source records attributed to H Petter.

10 recordsLinked to original sources
PubMed1992

Neuronal ectopia in tiger retina.

Ocular pathology in a ten week-old tiger is described. In the retinae of both glaucomatous eyes, venous congestion and scattered hemorrhages were observed; rare perivascular infiltrates were seen. The basal lamina of the inner limiting membrane was considerably thickened, and serous exudates were widely distributed within the vitreous body. The retina was studied with a series of specific antibodies. Müller (glial) cells were well developed and could be immuno-labelled by antibodies against both vimentin and glial fibrillary protein (GFAP). Neurofilament-specific antibodies revealed the presence of ganglion and horizontal cells, and of a nerve fibre layer which was unusually distant from the inner limiting membrane. Within both plexiform layers, scattered neuronal cells were found. The most important finding was the presence of cells between the nerve fibre layer and the inner limiting membrane, which could be immuno-labelled by neuron-specific antibodies, and which expressed thy typical morphology of migrating neuroblasts. It is suggested that this neuronal ectopia might be due to an inflammatory related reactive change in Müller cells which, in turn, might have lost their orderly guiding function for migrating neuroblasts.

Animals↗
PubMed1991

GABA-immunoreactive intrinsic and -immunonegative secondary neurons in the cat pineal organ.

The pineal organ of the cat was studied by postembedding gamma-aminobutyric acid (GABA) immunocytochemistry. Two polyclonal rabbit GABA antisera were used with light microscopic peroxidase and electron microscopic immunogold techniques. A considerable number of intrinsic neurons are scattered in the proximal portion of the pineal organ. Some of the nerve cells were GABA-immunoreactive; other neurons as well as pinealocytes and glial/ependymal cells were immunonegative. A few GABA-immunoreactive neurons behave like CSF-contacting neurons by penetrating the ependymal lining of the pineal recess. GABA-immunoreactive neurons were more frequently found in the subependymal region. Small bundles of thin immunoreactive unmyelinated and thick immunoreactive myelinated nerve fibers occurred in the proximal pineal, especially near the habenular commissure. There were synapses of various types between GABA-immunoreactive and -immunonegative fibers. Myelinated immunoreactive axons seemed to loose their sheaths after entering the organ. Axon-like processes of pinealocytes terminated on dendrites of immunonegative neurons present near the posterior and habenular commissures. The axons of these neurons were found to join the commissural fibers and may represent a pinealofugal pathway conducting information originating from pinealocytes. The pinealocytic axons forming ribbon-containing synapses on dendrites of secondary neurons speak in favor of the sensory-cell nature of the pinealocytes. The pinealopetal myelinated GABA-immunoreactive axons and the intrinsic "GABA-ergic" neurons are proposed to inhibit the action of intrapineal neurons on which the pinealocytic axons terminate.

Animals↗
PubMed1990

[Efferent projections of "classical" peptidergic neurons of the neurosecretory system of the telencephalon in reptiles (Scincus scincus L. and Chalcides ocellatus Forskal; Lacertilia, Squamata].

In both species of lacertilian reptiles investigated, the peptidergic hypothalamic supraoptic and paraventricular nucleus project with efferents to the telencephalon, to caudal parts of the brain, and to the spinal cord. The marked system of efferents of the "classic" peptidergic neurosecretory nuclei to the telencephalon was mapped. The unlabeled peroxidase-antiperoxidase immunocytochemical procedure revealed at the light microscopical level neurophysin- respectively mesotocin- or vasotocin-containing exohypothalamic fibres in the septal area, in subcortical regions (ventral striatum and hypopallium), and in all layers of the cortical areas (medial, dorsal and lateral cortex). Within the different parts of the brain, there seems to be a characteristically quantitative ratio of the mesotocin and vasotocin fibres. The terminals of the exohypothalamic fibres contact perikarya and processes of neurons of the target regions intimately. In a selected area, peptidergic synapses could be demonstrated at the electron microscopical level using an ultrahistochemical method. It is assumed that the nonapeptides mentioned are released from the fibre terminals and then act as neurotransmitters/neuromodulators influencing different brain functions.

Animals↗
PubMed1989

[Immunohistochemical studies on pituitary adenomas in Wistar rats. 1. Demonstration of ACTH, LH, neurophysin, oxytocin and vasopressin in the pituitary of Ico:WIST rats from chronic toxicity studies].

Spontaneous pituitary adenomas are common in certain strains of the laboratory rat. Investigations of Wistar rats of two years chronic toxicity studies revealed pituitary tumors in 50% of the females and 26% of the males. The morphology of the spontaneous changes in the pituitary gland was investigated with immunohistochemical and histological methods. The peroxidase-antiperoxidase (PAP) technique was used to localize different hormones (LH, ACTH) in cells of the pars intermedia and pars distalis as well as neurophysin, oxytocin and vasopressin the terminals of the classic neurosecretory system of the pars nervosa. The results show that most of the neoplasms were endocrinologically inactive chromophobe adenomas of the pars distalis.

Adenoma↗
PubMed1989

[Morphological and immunohistochemical investigation of serotonergic neurons in the dorsal raphe nucleus of Wistar rats].

The serotonergic neurons of the nucleus raphe dorsalis (NRD) of the adult male Wistar rat were characterized morphologically using Nissl and Golgi-Kopsch techniques, fluorescence histochemistry as well as a peroxidase-antiperoxidase (PAP) immunocytochemical method employing specific antibodies to serotonin. 1. The numerous serotonin-positive neurons within (and around) the NRD exhibit--in agreement with data of the literature--characteristic heterogeneous distribution patterns both in rostro-caudal direction and also dorsoventral particularly in the mesencephalic part, the zone of the largest extension of the nucleus. Several groups with high cell concentration could be divided. The neurons differ in their immunoreactivity. 2. Based on different criteria, especially the number and arrangement of dendrites as well as the cell shape, three types of serotonergic neurons could be identified: multipolar, fusiform (bipolar) and small ovoid ones. A parallel analysis in Golgi-stained material offers the possibility for more detailed studies and further characterization. 3. With respect to functional interpretations some morphological peculiarities seem to be remarkable, e.g. the close relation between several neurons, the tight dendritic contact to many blood vessels or the formation of a dense serotonin-positive fiber plexus along the floor of the aqueductus and fourth ventricle. Studies, following stereotactic application of the neurotoxin 5.7-dihydroxytryptamine into the NRD, show furthermore that the majority of serotonergic neurons--independently of the cell type--reveals signs of cell degeneration. The findings presented confirm previous studies and should provide also further insights into the morphology of the 5-HT neurons of rat NRD as well as for the explanation of functional aspects.

Animals↗
PubMed1986

[Somatostatin in lamprey brains (Lampetra planeri Bloch)].

In the brain of larval and adult lampreys (Lampetra planeri Bloch) a distinct somatostatin system using somatostatin antiserum with the unlabeled peroxidase-antiperoxidase technique was demonstrated. The immune reactive perikarya are localized in the nucleus ventralis hypothalami and they are restricted to this nucleus without exception. A small number of immune positive efferences invades the commissura praeinfundibularis. In the neurohypophysis localized caudally from this commissure and in the adenohypophysis no somatostatin fibres could be visualized. Most of the efferences leave the hypothalamus as exohypothalamic fibres and form a system of somatostatin fibres which extends from the telencephalon to the medulla oblongata. Regionally, this system is organized in a net-like manner.

Animals↗
PubMed1985

[Immunocytochemical studies on the possible involvement of the classical neurosecretory system in the cerebral processes of cardiovascular regulation].

The distribution and the cytomorphology of neurophysin- and oxytocin-producing cells of the classic neurosecretory system of the rabbit were investigated at light microscopic level using the peroxidase-antiperoxidase (PAP) technique. Our results show that the neurons are distributed not only in the paraventricular and supraoptic nuclei, but as constituents of the suprachiasmatic nucleus and different cell clusters in the diencephalon they have a broader distribution than hitherto has been assumed. The light microscopic analysis of the exohypothalamic hypothalamo-rhombencephalic pathway shows that its fibres are closely related to neurons of the nucleus of the tractus solitarii and the dorsal motor nucleus of vagus. Following light microscopic observations suggesting that these fibres terminate on neurons in these nuclei, an immuno-electron microscopic study was undertaken. Using the pre-embedding technique, specific reaction products were observed indicating both neurophysin and oxytocin in axo-dendritic and axo-somatic synapses. These peptide-containing terminals do not seem to differ in any way from classic transmitter-containing synapses in the brain. The synaptic contacts between hypothalamo-rhombencephalic fibres on the one hand and neurons of the nucleus tractus solitarii and the dorsal motor nucleus of vagus on the other might be the morphological representation of an involvement of the paraventricular nucleus in cerebral cardiovascular regulation.

Animals↗
PubMed1981

Immunocytochemical investigation of the subcommissural organ in the rat.

The results of a preliminary immunocytochemical investigation on the subcommissural organ (SCO) in rats show that (1) Reissner's fiber (RF) or essential compounds of the RF are produced by the SCO, (2) the immunoreactive material is produced in the epithelial cells of the SCO as well as in the hypendymal cells, and (3) the immunoreactive material of the SCO belongs to a category of endogenous peptides to date not demonstrable immunocytochemically in other brain structures.

Animals↗