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Biomedical subjects

B Vigh

Publications and source records attributed to B Vigh.

At least 37 records · Page 2Linked to original sources
PubMed1989

The pinealocyte forming receptor and effector endings: immunoelectron microscopy and calcium histochemistry.

The pinealocytes--the main cellular elements of the pineal organ--are polarized, displaying a (photo)receptor and an axonic effector cell pole. The receptor endings are of two main types: they bear rod-type or cone-type outer segments characterized by the presence of immunoreactive opsin-, S-antigen- and vitamin A-binding sites. The effector pole may form ribbon-containing synapses on the secondary pineal neurons, and/or neurohormonal terminals on the basal lamina of the pineal nervous tissue. Applying potassium pyroantimonate (PPA) to electron-microscopic histochemistry, we found in the frog that both effector terminals and photoreceptor outer segments contained a large amount of Ca-pyroantimonate deposit similar to retinal cones and rods. Rods and rod-like pinealocytes contained more deposits than cones. The higher concentration of calcium on the cell membranes of dark pinealocytes in the rat may be connected with their rod-like character. In the frog, a high amount of calcium seemed to be concentrated in the photoreceptor effector terminals, especially around their synaptic ribbons, and in myeloid bodies of the pineal ependyma and retinal pigment epithelium. Calcium was richly found in or around corpora arenacea in the human and rat pineal. It is suggested that the formation of concrements may be connected with the high demand of Ca-exchange of pinealocytes for their receptor and effector membrane functions. In the rat, lymphocytes were found to migrate through the wall of the vena magna of Galen and to closely contact pinealocytes, presumably to receive immunological information as an additional pineal output.

Animals↗
PubMed1989

Pineal corpora arenacea produced by arachnoid cells in the bat Myotis blythi oxygnathus.

There are corpora arenacea among the cell layers of the arachnoid on the dorsal surface of the pineal organ of the bat (Myotis blythi oxygnathus). The pineal arachnoid consists of electron lucent cells connected by cell injunctions to flat sheets and sandwiched on both sides by electron-dense cell rows. Among the superficial cell layers, collagen fibrils form loose bundles. In the electron-lucent cells, pinocytotic vesicles, rough surfaced endoplasmic reticulum, active Golgi areas and granular vesicles of various sizes can be found. Electron dense cells display fewer cytoplasmic organelles than the light ones. Lying between and below the hemispheres and cerebellum the pineal arachnoid does not contact the dura mater directly, therefore it continues on its both sides into arachnoid trabeculae. Corpora arenacea occur in lacunar enlargements of the arachnoid, first of all in the thickened dorsal portion of the pineal leptomeninx. The acervuli are insulated by collagen fibrils and exhibit concentric layers of various density. Needle-shaped structures resembling hydroxyapatite crystals were found in these concentric layers. There was no sign of formation of acervuli in the pinealocytes or elsewhere in the pineal nervous tissue proper. These findings confirm that view that corpora arenacea can be produced by the pineal arachnoid. The formation of acervuli is accompanied by secretory and resorptive phenomena of arachnoid cells.

Animals↗
PubMed1989

Immunoelectron microscopy of rhodopsin and vitamin A in the pineal organ and lateral eye of the lamprey.

Rhodopsin- and vitamin A-immunoreactive sites were studied in the pineal organ of the larval and adult brook lamprey (Lampetra planeri Bloch), as well as in the retina of the larval lateral eye, at the electron microscopic level. In the pineal organ, several types of photoreceptor cells could be distinguished by their morphology and the immunoreactivity of their outer segments. The different kinds of photoreceptor cells were located at different levels of the pineal organ according to their distance from the "pineal window". The most superficial level, the so-called pellucida, appears to represent an exclusively "cone-type" area containing slender, rhodopsin-immunonegative (UV-blue-sensitive?) photoreceptors only. The second level, the pineal retina, contained predominantly rod-type photoreceptors, i.e., large, strongly rhodopsin-immunopositive (green-sensitive) photoreceptors medially, and few, small, weakly rhodopsin-immunopositive (blue-green-sensitive?) cells bilaterally. At the deepest level, the pineal atrium, there were both rod- and cone-type photoreceptor cells, the latter possibly representing red-sensitive elements. Vitamin A immunoreactivity was found in the outer segments of the pineal photoreceptor cells, in the cytoplasm and mitochondria of inner segments and perikarya, as well as in nuclear euchromatin and compact nucleoli. A similar gold labelling of organelles was observed in the ependyma and pineal neurons. The vitamin A immunoreaction of the outer segments suggests retinoids are present as chromophores of the photopigments. In the peripheral retina of the larval lateral eye, vitamin A immunoreactivity was found in some organelles of the undifferentiated photoreceptor cells, neurons, pigment epithelium and Müllerian cells. The localization of immunoreactive vitamin A in nuclei, nucleoli and cytoplasm including mitochondria appears to strengthen the case for an interaction of retinoids in the function of these organelles.

Animals↗
PubMed1988

Immunocytochemical localization of vitamin A in the retina and pineal organ of the frog, Rana esculenta.

Vitamin A immunoreactive sites were studied in the retina and pineal organ of the frog, Rana esculenta, by the peroxidase antiperoxidase, avidin-biotinperoxidase and immunogold methods. In dark-adapted material, strong immunoreaction was found in the outer and inner segments of the photoreceptor cells of both retina and pineal organ, as well as in the pigment epithelium, retinal Müller cells and pineal ependymal cells. In light-adapted retina, cones and green (blue-sensitive) rods were immunopositive. At the electron microscopic level, immunogold particles were found on the membranes of the photoreceptor outer segments as well as on the membranes of the endoplasmic reticulum and mitochondria. Individual retinal photorecptor cells exhibited strong immunoreaction in the distal portion of the inner segment, the ciliary connecting piece and the electron-dense material covering the outer segment. In the pigment epithelium, the immunolabeling varied in intensity in the basal and apical cytoplasm and phagocytosed outer segments. The immunocytochemical results indicate that retinoids (retinal, retinol and possibly retinoic acid) are present not only in the photoreceptor cells of the retina but also in those of the pineal organ. The light-dependent differences in the immunoreactivity of vitamin A underlines its essential role in the visual cycle of the photopigments. Our results suggest that the pineal ependyma plays a role comparable to that of the Müller cells and pigment epithelium of the retina with regard to the transport and storage of vitamin A. The presence of a retinoid in nuclei, mitochondria and cytoplasmic membranes suggests an additional role of vitamin A in other metabolic processes.

Animals↗
PubMed1986

Three types of photoreceptors in the pineal and frontal organs of frogs: ultrastructure and opsin immunoreactivity.

The pineal complex in frogs (Rana esculenta, R. temporaria, R. tigrina, R. arvalis) was studied by conventional electron microscopy and postembedding rhodopsin immunoelectron microscopy. Three types of photoreceptor cells were found in both the pineal and frontal organs. In the pineal organ, most of the photoreceptors exhibited rhodopsin-immunoreactive outer segments and large inner segments with a large ellipsoid of densely packed mitochondria ("rod-like" photoreceptors). A small number of photoreceptors was rhodopsin-immunonegative ("cone-like" photoreceptors). In both Rana esculenta and R. temporaria, the latter were either supplied with an oil droplet and an ellipsoid in their inner segment, or they were electron-lucent with a small inner segment without an ellipsoid. In contrast, the frontal organ displayed many immunonegative "cone-like" outer segments and few rhodopsin-immunoreactive "rod-like" photoreceptors. In both organs, the basal processes of the photoreceptor cells were found to form ribbon-containing axonal pedicles which synapsed with the dendrites of secondary neurons. The latter rarely received any further afferences by conventional synapses. The frog pineal organ is considered a predominantly "rod-type" and the frontal organ a "cone-type" photosensory organ. The presence of three kinds of pineal/frontal photoreceptors is discussed in connection with the occurrence of different photopigments (rhodopsin/porphyropsin, iodopsin, ultraviolet and/or blue pigments) enabling the animal to discriminate by the pineal complex environmental light in various ranges of the spectrum.

Animals↗
PubMed1986

Light and electron microscopy of S-antigen- and opsin-immunoreactive photoreceptors in the retina of turtle, chicken, and hedgehog.

S-antigen and opsin-immunoreactive sites were studied in the retina of turtle (Pseudemys scripta elegans), chicken (Gallus domesticus), and hedgehog, (Erinaceus roumanicus) by light-microscopic avidin-biotin-peroxidase and electron-microscopic protein A-gold and immunoglobulin-gold (immunogold) techniques. In general, S-antigen and opsin immunoreactions were exclusively localized to certain photoreceptors of the retinae studied. In turtle and chicken, strong S-antigen immunoreactivity was found in the outer and inner segments, perikarya and synaptic bases of rod photoreceptors. Some--apparently green--single cones also exhibited immunoreactive outer and inner segments. In hedgehog, the inner segments, perikarya and pedicles of rods displayed immunoreaction of varying intensities. In all three species there was an accumulation of immunogold particles on the distal portion of the inner segment, the connecting piece and the proximal portion of the outer segment. Opsin immunoreactivity was found in the outer segments of rod photoreceptors, and in those of--apparently green--single cones of turtle and chicken. The localization and significance of the S-antigen immunoreaction is discussed in connection with the occurrence of different photopigments in the retinae studied. The correlation of the presence of S-antigen and of either rhodopsin or porphyropsin in rod and--apparently green--single cone photoreceptors was emphasized.

Animals↗
PubMed1986

Different types of pinealocytes as revealed by immunoelectron microscopy of anti-S-antigen and antiopsin binding sites in the pineal organ of toad, frog, hedgehog and bat.

S-antigen- and opsin-immunoreactive sites were studied in the pineal organ of toad (Bufo bufo), frog (Rana tigrina), hedgehog (Erinaceus roumanicus) and bat (Myotis myotis) by light microscopic avidin-biotin-peroxidase and electron microscopic immunoglobulin-gold (immunogold), protein A-gold and avidin-biotin-ferritin techniques. The corresponding retinas served as reference tissues. A large number of photoreceptors of toad and frog pineal organ exhibited either strong or weak S-antigen immunoreaction in the outer segments, perikarya and basal processes. A small number of photoreceptors was S-antigen-negative. In general, the intensity of the reaction was stronger in the immunoreactive outer segments of the pineal organ than in those of the rods and certain cones of the retina. In hedgehog and bat, the perikarya and processes of the pinealocytes were either strongly or weakly S-antigen-positive or they lacked immunogold labeling. By use of an antibovine rhodopsin antiserum either strong or weak opsin immunoreactivity was found in the pineal outer segments of toad and frog. A small number of pineal photoreceptors lacked opsin antigenic sites. Double labeling with both antibovine S-antigen and antibovine opsin antisera showed that the opsin immunoreaction was present in the outer segments which also exhibited S-antigen immunoreaction. In the pineal organ of hedgehog and bat, no opsin immunoreaction was observed with the antisera used. It is proposed that in the pineal organ at least two types of photoreceptors are present: one "rod-type" elaborating rhodopsin accompanied by S-antigen and one (or two) "cone-type(s)" using an unknown photopigment(s). Obviously, the different photoreceptors enable the animal to perceive the different wavelengths of the light spectrum.

Animals↗
PubMed1985

Sensory cells of the "rod-" and "cone-type" in the pineal organ of Rana esculenta, as revealed by immunoreaction against opsin and by the presence of an oil (lipid) droplet.

The pineal organ of the frog, Rana esculenta, was studied by use of light- and electron-microscopic methods including immunoreaction against opsin. Most of the morphologically classified cone-type outer segments of the pineal photoreceptors reacted with antisera against opsin of the bovine retina that is dominated by rods. Some of the outer segments of pineal photoreceptor cells remained unstained in accord with the reference tissue, the frog retina, where generally the rods were opsin-positive and most of the cones opsin-negative. The opsin-negative outer segments of pineal photoreceptors were found in continuity with inner segments each containing a large oil (lipid) droplet. These oil droplets stained intensely with osmic acid, Sudan III, Sudan Black B or Scharlach R in cryostat sections, and were soluble in lipid solvents. In ultrathin sections of osmicated material, the oil droplets were homogeneous and of varying electron density. Approximately one tenth of the pineal photoreceptors contained oil droplets and at the same time possessed opsin-immunonegative outer segments. Since in the retina oil droplets and a negative immunoreaction against bovine opsin are characteristic of cones, we suggest that in the pineal organ they also mark "cone-type" photoreceptors scattered among "rod-type" photoreceptors, the latter displaying a positive immunoreaction with the antisera used.

Animals↗
PubMed1984

Opsin-immunoreactive outer segments of photoreceptors in the eye and in the lumen of the optic nerve of the hagfish, Myxine glutinosa.

Opsin-immunoreactive sites in the eye and optic nerve of the hagfish, Myxine glutinosa, were studied by use of light-microscopic pre- and postembedding peroxidase-antiperoxidase or avidin-biotin-peroxidase techniques, and the immuno-electron-microscopic protein A-gold method. At the light-microscopic level, a strong opsin immunoreaction was obtained on the outer segments of the photoreceptor cells with sheep and rat antibodies against bovine (rhod)opsin. These outer segments were located in the marginal photoreceptor space and in follicles of the retina, as well as in the tubular lumen of the optic nerve. Ultrastructurally, two classes of outer segments can be distinguished; most of them exhibited a strong antiopsin reaction, while certain elements lacked immunoreactivity with the antisera employed. The protein A-gold particles marked opsin-immunoreactive sites on the photoreceptor membranes. The presence of opsin-immunoreactive material in the retina and optic nerve of the hagfish strengthens the view that this primitive eye lacking a cornea, lens and vitreous body is engaged in light perception. The morphological similarity between the eye and pineal tissue is discussed in connection with the absence of a pineal organ in this species.

Animals↗
PubMed1984

Serotonin and opsin immunoreactivities in the developing pineal organ of the three-spined stickleback, Gasterosteus aculeatus L.

5-hydroxytryptamine (5-HT, serotonin)- and opsin-immunoreactive sites were studied in the developing pineal complex of the stickleback, Gasterosteus aculeatus L., by use of light-microscopic indirect immunoperoxidase techniques. 5-HT immunoreactivity first occurs in the pineal organ at the age of 80 h after fertilization and appears to be localized in cells of the photoreceptor type. The outer segments of a few pineal photosensory cells exhibit opsin immunoreactivity at the age of 84 h after fertilization. The number of cells seems to increase until the pineal organ is completely developed. The increase in the number of 5-HT immunoreactive perikarya runs parallel in time to that of the opsin-immunoreactive outer segments. The cells of the parapineal organ show neither opsin nor 5-HT immunoreactivity. The retina of the embryonic stickleback does not display opsin immunoreactivity until after hatching, which takes place about 144 h after fertilization. These results suggest, in the three-spined stickleback, an earlier light-perception capacity for the developing pineal organ than for the retina.

Animals↗
PubMed1983

The pineal organ of Raja clavata: opsin immunoreactivity and ultrastructure.

The pineal organ of Raja clavata was studied by light and electron microscopy, including the immunocytochemical antiopsin reaction. The pineal organ of the ray consists of three portions: (i) a large proximal pineal, (ii) a long tube-like connecting stalk, and (iii) a short distal terminal enlargement. This latter end-vesicle lies in the deep connective tissue layers of the braincase. All portions of the pineal are composed of pinealocytes, intrinsic neurons, ependymal/glial cells, and bundles of nerve fibers embedded in thin neuropil formations. The inner segments of the pinealocytes protrude into the lumen in all parts of the organ and usually contain basal bodies and numerous mitochondria. Often, two outer segments were found to arise from the basal bodies of a single inner segment. By means of light-microscopic immunocytochemistry the outer segments showed a strong antiopsin reaction. The axons of the pinealocytes form ribbon-containing synapses on dendrite-like profiles, which appear to belong to the intrinsic pineal neurons. There are other axo-dendritic synapses established by presynaptic terminals lacking ribbons and containing granular and synaptic vesicles. Pineal neurons may contain granular vesicles approximately 60-100 nm in diameter; their processes contribute to the bundles of unmyelinated axons. The fine structural organization of the pineal organ and the opsin immunoreactivity of the outer segments of the pinealocytes indicate a photoreceptive capacity of the organ. The double outer segments represent a peculiar multiplication of the photoreceptor structures.

Animals↗
PubMed1983

Cerebrospinal fluid-contacting neurons, sensory pinealocytes and Landolt's clubs of the retina as revealed by means of an electron-microscopic immunoreaction against opsin.

Opsin-immunoreactive sites of hypothalamic cerebrospinal fluid (CSF)-contacting neurons, pinealocytes and retinal cells were studied in various vertebrates (Carassius auratus, Phoxinus phoxinus, Triturus cristatus, Bombina bombina, Rana esculenta) by means of postembedding immuno-electron microscopy with the use of the protein A-gold labeling method. The retina of the rat served as a general reference tissue for the quality of the immunocytochemical reaction. A strong opsin immunoreaction (rat-antibovine opsin serum) was obtained in the rod-type outer segments of photoreceptors in the retina of all species studied. Cone-type outer segments exhibited only very few antigenic binding sites. In the pineal organ of the goldfish and the frog, outer segments of the photoreceptor cells displayed strong immunoreactivity. No immunoreaction was found in hypothalamic CSF-contacting neurons and Landolt's clubs of nerve cells of the bipolar layer of the retina. The morphological similarity between the ciliated dendritic terminal of the Landolt's club and the intraventricular dendritic ending of the CSF-contacting neurons is emphasized.

Animals↗
PubMed1983

Opsin-immunoreactive outer segments in the pineal and parapineal organs of the lamprey (Lampetra fluviatilis), the eel (Anguilla anguilla), and the rainbow trout (Salmo gairdneri).

The pineal complex of Lampetra fluviatilis, Anguilla anguilla and Salmo gairdneri was studied by means of the indirect immunohistochemical antiopsin reaction. Opsin-immunoreactive material was demonstrated in the outer segments of the photoreceptor cells in the pineal organ of all three species investigated. In the lamprey, the opsin-positive outer segments were located in the lumen of the pineal vesicle and atrium. In the two teleost species, the immunoreactive outer segments were observed in abundance in the pineal end-vesicle and stalk. These structures were found to accumulate in the prominent initial portion of the pineal stalk of the eel. In the rainbow trout, immunoreactive outer segments occurred in the wide orifice of the pineal recess at the roof of the third ventricle. In addition, outer segments of photoreceptor cells of the parapineal organ ("parapinealocytes") displayed opsin immunoreactivity. In the lamprey, opsin immunoreactivity was restricted to the central portion of the ventral parapineal retina, while the parapinealocytes in the lateral portions did not bind the antibody. In the two teleosts, immunoreactive outer segments displayed a scattered pattern. These immunocytochemical results provide direct evidence that the photosensitivity of the pineal demonstrated electrophysiologically in lampreys and teleosts (cf. Dodt 1973) is based on an opsin-containing photopigment. The presence of opsin in cells of the parapineal organ strengthens the view that also this organ may be capable of direct light perception. In the lamprey, the exclusive opsin immunoreactivity of a circumscribed group of parapineal cells suggests the existence of two types of parapinealocytes. The significance of opsin-containing photoreceptor outer segments occurring in the most proximal portion of the teleost pineal stalk is discussed, especially with regard to the interpretation of results obtained from pinealectomy experiments.

Animals↗
PubMed1983

Cerebrospinal fluid-contacting neurons of the central canal and terminal ventricle in various vertebrates.

Cerebrospinal fluid (CSF)-contacting neurons were studied by means of electron microscopy in the spinal cord and/or terminal ventricle of the ray, Raja clavata (Elasmobranchii), the opossum, Didelphis virginiana (Marsupialia), the mouse, Mus musculus, and the guinea pig, Cavia cobaya (Rodentia). Dendrites of the CSF-contacting neurons in the spinal cord of the ray penetrate the ependyma of the central canal and form terminals bearing stereocilia. Axons apparently belonging to these neuronal perikarya terminate on the basal lamina of the spinal cord near the fila of the radix ventralis. In the opossum, a representative of metatherian mammals, the dendritic terminals of the CSF-contacting neurons resemble those of the phylogenetically ancient lower vertebrates and are endowed with many stereocilia. In such eutherian mammals as the mouse and the guinea pig, the corresponding stereocilia are usually less developed. There are numerous CSF-contacting neurons in the wall of the terminal ventricle of the mouse. Since the dendritic terminals of the spinal CSF-contacting neurons resemble those of known sensory cells and the axon terminals on the basal lamina resemble ultrastructurally neurosecretory endings, we suppose that the former are receptive to stimuli exerted by the internal (ventricular) CSF and capable of translating them into a neurosecretory output directed toward the external (subarachnoid) CSF. With their periradicular terminations the axons of the CSF-contacting neurons establish an extended, special site for neurosecretory release along the ventrolateral sulcus of the ray spinal cord.

Animals↗
PubMed1983

CSF-contacting and other somatostatin-immunoreactive neurons in the brains of Anguilla anguilla, Phoxinus phoxinus, and Salmo gairdneri (Teleostei).

A system of somatostatin-immunoreactive neurons was demonstrated in the brains of the eel, Anguilla anguilla, the European minnow, Phoxinus phoxinus, and the rainbow trout, Salmo gairdneri, by means of the light-microscopic indirect immunoperoxidase technique. In the anterior periventricular nucleus, somatostatin-immunoreactive cerebrospinal fluid (CSF)-contacting neurons display intensely stained intraventricular dendritic protrusions, perikarya, and axonal processes. The latter taper into a somatostatin-immunoreactive fiber plexus extending to the infundibulum, the proximal neurohypophysis, and the lateral and mammillary recesses. In addition, somatostatin-immunoreactive neurons were demonstrated in the magnocellular preoptic, entopeduncular and dorsolateral thalamic nuclei, further in the pretectal area and the ventrolateral tegmentum. Somatostatin-immunoreactive fiber bundles project via the stria medullaris toward the habenular nucleus; they also course in the dorsomedial-ventrolateral direction at the level of the pretectal-tegmental area, and within the ventral and dorsal tegmentum. The presence of somatostatin in a variety of different neurons of the teleost brain is discussed in connection with their tentative inhibitory function. The CSF-contacting neurons of the anterior periventricular nucleus are supposed to function as sensors that pass information from the CSF to the somatostatin system of the hypothalamus and/or other components of the neuroendocrine apparatus.

Animals↗
PubMed1983

The system of cerebrospinal fluid-contacting neurons.

Cerebrospinal fluid (CSF)-contacting neurons are located periventricularly or inside the brain ventricles; they contact the CSF via their dendrites, perikarya or axons. Most of the CSF-contacting nerve cells send dendritic processes into the ventricular cavity where they form ciliated terminals. These ciliated dendritic endings resemble those of known sensory cells, yet their role is still unknown. There are two types of CSF-contacting dendritic terminals. One bears solitary 9 X 2 + 0 cilia; it is present in different hypothalamic regions such as the paraventricular organ and the vascular sac. The magnocellular neurosecretory nuclei also contain CSF-contacting neurons, which probably furnish information about the parameters of the CSF for the regulatory function of the hypothalamo-hypophyseal system. CSF-contacting nerve cells of the parvocellular hypothalamic nuclei are suspected to participate in hypothalamo-adenohypophyseal regulation. A second type of CSF-contacting dendritic terminal bears many stereocilia and is found in the central canal of the spinal cord. This type of terminal is also supplied with a 9 X 2 + 2 kinocilium that may contact Reissner's fiber, the secretory material of the subcommissural organ. Resembling mainly mechanoreceptors, these spinal CSF-contacting neurons appear to form axon terminals of the neurosecretory type at the external circumference of the spinal cord. Developing and/or regressing photoreceptor cells of the retina and pineal complex may display a similar dendritic structure characteristic of hypothalamic CSF-contacting neurons. Axons penetrating into the ventricles innervate the apical surface of the ependyma and/or the CSF-contacting dendritic terminals. Some bipolar neurons of the retina form so-called Landolt's clubs; these may be considered as the retinal component of the CSF-contacting neuronal system. Since in the lancelet nearly all nerve cells contact the CSF, the CSF-contacting neurons represent a specialized, but phylogenetically old cell type, a "protoneuron" in the vertebrate brain. They may be derived phylogenetically by inversion of the ciliated neurons found in the plate-like nervous system of more primitive deuterostomians.

Amphibians↗