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1.
Summary Retinopetal neurons were visualised in the telencephalon and diencephalon of an air-breathing teleost fish, Channa punctata, following administration of cobaltous lysine to the optic nerve. The labelled perikarya (n=45–50) were always located on the side contralateral to the optic nerve that had received the neuronal tracer. The rostral-most back-filled cell bodies were located in the nucleus olfactoretinalis at the junction between the olfactory bulb and the telencephalon. In the area ventralis telencephali, two groups of telencephaloretinopetal neurons were identified near the ventral margin of the telencephalon. The rostral hypothalamus exhibited retrogradely labelled cells in three discrete areas of the lateral preoptic area, which was bordered medially by the nucleus praeopticus periventricularis and nucleus praeopticus, and laterally by the lateral forebrain bundle. In addition to a dorsal and a ventral group, a third population of neurons was located ventral to the lateral forebrain bundle adjacent to the optic tract. The dorsal group of neurons exhibited extensive collaterals; a few extended laterally towards the lateral forebrain bundle, whereas others ran into the dorsocentral area of the area dorsalis telencephali. A few processes extended via the anterior commissure into the telencephalon ipsilateral to the optic nerve that had been exposed to cobaltous lysine. However, the ventral cell group did not possess collaterals. In the diencephalon, retinopetal cells were visualised in the nucleus opticus dorsolateralis located in the pretectal area; these were the largest retinopetal perikarya of the brain. The caudal-most nucleus that possessed labelled somata was the retinothalamic nucleus; it contained the largest number of retinopetal cells. The limited number of widely distributed neurons in the forebrain, some with extensive collaterals, might participate in functional integration of different brain areas involved in feeding, which in this species is influenced largely by taste, not solely by vision.  相似文献   
2.
Summary A negative feedback interaction between luminosity type horizonatal cells (HCs) and green-sensitive cones generates the long-wavelength-sensitive depolarizing response in biphasic chromaticity type HCs. This interaction is suppressed in the dark and is potentiated by light adaptation of the retina. HCs are morphologically plastic; during light adaptation, their dendritic terminals within cone pedicles extend, giving rise to spinules. This paper examines whether there is a quantitative correlation between the time course of light-dependent formation of the spinules and enhancement of the feedback interaction. The strength of the feedback interaction in isolated retinac of the roach was determined as the neutral wavelength at which reversal of spectral response polarity occurred in biphasic HCs. A good correlation was found between the neutral wavelength and the spinule/ribbon ratios of retinae. Biphasic HCs were intracellularly stained with horseradish peroxidase and the correlative ultrastructure of the contacted pedicles was examined. Neutral wavelength was found to be correlated with the spinule number, weighted according to the number of synaptic contacts mediating feed-forward transmission. The latter was estimated from the total number of labelled Cb/H2 HC processes (central and lateral) at synaptic triads. A model in which spinules mediate the negative feedback interaction of HCs in the retina of cyprinid fish is presented.  相似文献   
3.
4.
Synaptic ribbons are trilaminated plate-shaped presynaptic densities of certain types of receptor cells and neurons. In cone photoreceptors, these structures dissassemble and reassemble in response to light and to a variety of other stimuli. We used the lithium-ionenhanced disassembly and reassembly of synaptic ribbons to characterize structural intermediates in these cyclic changes. A few minutes after exposure of isolated retinas from the crucian carp (Carassius carassius) to lithium, ribbons fragmented into 50-nm-sized dense globular structures. These small spheres were concentrically surrounded by synaptic vesicles attached to them by stalk-like fine bridging filaments. Disassembly always started at the free cytoplasmic edges of the ribbons and proceeded toward the membrane-associated edges. As the disassembly process never started at the membraneanchored site, synaptic ribbons appeared to be polarized structures with functionally different ends. Spheres were subjected to further depolymerization. They disintegrated into clusters of small granular material and disappeared after ca. 45 min of lithium treatment. Spheres were not observed during the reassembly of synaptic ribbons, indicating that the assembly of synaptic ribbons proceeds via smaller subunits.  相似文献   
5.
Summary The caudal spinal cord of the coho salmon was investigated by means of immunocytochemistry using antisera against serotonin, urotensin I, urotensin II, somatostatin and a urea-extract of bovine Reissner's fiber (AFRU). Populations of serotonin-immunoreactive (IR) neurons were found rostral and dorsal to the urophysis in close spatial association with caudal secretory neurons. Thick, smooth serotonin-IR processes extended toward the external surface of the spinal cord where they displayed conspicuous terminal dilatations. Thin, beaded serotonin-IR fibers appeared to innervate populations of caudal secretory and somatostatin-IR cerebrospinal fluid-contacting neurons. Most caudal neurosecretory cells displayed both urotensin I and urotensin II immunoreactivities; only a minority reacted exclusively with either urotensin I or urotensin II antisera. Urotensin II-IR and somatostatin-IR cerebrospinal fluid (CSF)-contacting neurons were found as an integral component of the central canal wall in the caudal spinal cord and filum terminale; their dendritic processes appeared to contact Reissner's fiber, which displayed a weak AFRU-immunoreactivity while inside the central canal, but became strongly reactive in the interior of the terminal ventricle as it formed the massa caudalis. The distribution of serotoninergic processes points to a regulatory role in the function of caudal secretory and CSF-contacting neurons and to a putative serotonin release into the subarachnoid space and/or meningeal vasculature. It is also suggested that the CSF-contacting neurons of the central canal may participate in a feedback mechanism controlling the secretory activity of the subcommissural organ.Supported by Grant A/1095-1 from the International Foundation for Science, Sweden, to C.Y.; Grant I/63-476 from Volkswagen-Stiftung to E.R.; and Grant S-85-39 from the Dirección de Investigaciones, Universidad Austral de Chile  相似文献   
6.
Biogenic peptides and amines associated with the chromaffin tissue in Atlantic cod (Gadus morhua), rainbow trout (Oncorhynchus mykiss), European eel (Anguilla anguilla), spiny dogfish (Squalus acanthias) and Atlantic hagfish (Myxine glutinosa) were identified utilizing immunohistochemical techniques. Within the posterior cardinal vein (PCV) in cod, trout and eel, a subpopulation of chromaffin cells displayed immunoreactivity to tyrosine hydroxylase (TH) and dopamine--hydroxylase (DH) but not to phenylethanolamine-N-methyltransferase (PNMT). TH-like immunorectivity was observed within cells in hagfish hearts. Nerve fibres displaying vasoactive intestinal peptide (VIP) immunoreactivity and pituitary adenylyl cyclase activating peptide (PACAP) immunoreactivity innervated cod, trout and ell chromaffin cells. In eel, neuropeptide Y (NPY)-like and peptide YY (PYY)-like immunoreactivity was located within cells in the PCV, including chromaffin cells. Serotonin-like immunoreactivity was observed within eel and cod chromaffin cells and in hagfish hearts. In the dogfish axillary bodies, nerves displaying TH-like, VIP-like, PACAP-like, substance P-like and galanin-like immunoreactivity were observed. These results are compared with those of other vertebrates, and potential roles for these substances in the control of catecholamine release are suggested.  相似文献   
7.
Summary The follicular epithelial layers of the developing ovary of two cichlid species were examined by electron microscopy for evidence of steroid secretion. As each oocyte grew, its follicular cell layers increased in height, eventually becoming somewhat columnar; no development could be detected in follicle cells of non-activated oocytes. Isolated cells close to capillaries in the thecal layer developed large amounts of smooth membrane indicative of steroidogenesis, appearing similar at maturity to testicular Leydig cells. In Cichlasoma nigrofasciatum the mitochondria of differentiated thecal elements contained microtubule-like inclusions. It is suggested that these cells may produce estrogens during vitellogenesis.In developing granulosa cells, active synthesis of granular endoplasmic reticulum occurred. This membrane appeared to arise from the nuclear envelope, and in the pre-ovulatory stage was always intermediate between smooth and granular forms, being only partly associated with ribosomes. Evidence for steroid biosynthesis in the granulosa at this time was therefore equivocal. Evidence was found of transfer of micropinocytotic vesicles from the granulosa cells into the ooplasm.The fate of the post-ovulatory follicle was investigated in Cichlasoma. Thecal elements remained separate from granulosa and unchanged in ultrastructure for up to ten days. The granulosa cells proliferated and differentiated within a few hours after ovulation into a cell type containing much smooth reticulum, characteristic of steroidogenesis. However, after approximately three days numerous signs of degenerative processes became visible. The significance of the observed ultrastructural changes in relation to endocrine function is discussed.  相似文献   
8.
Zusammenfassung In vergleichend autoradiographischen Untersuchungen wurde der Einbau von percutan applizierten 3H-Uridin, 3H-Histidin und 3H-Glucose in die wichtigsten Organsysteme (Epidermis, ZNS, Muskeln, Chorda, Leber, Kiemendarm, Darm) von Branchiostoma lanceolatum (Acranier) und Brachydanio rerio (Teleosteer) nach Inkorporationszeiten von 11 min bis zu 7 Tagen verfolgt. Der Stoffwechsel der markierten Substanzen in den einzelnen morphologisch miteinander zu homologisierenden Organen war bei den beiden Spezies sehr ähnlich, bei Branchiostoma allerdings (mit Ausnahme des ZNS) 4–5mal stärker als bei Brachydanio. Bei dem letzteren wurde außerdem eine zeitliche Verzögerung in der Tracer-Aufnahme (lag-Phase) beobachtet. Insbesondere der ZNS-Stoffwechsel von Acraniern zeigte ähnliche Charakteristika wie der von Vertebraten: Verbleib des Hauptanteils der neusynthetisierten RNS im Perikaryon, axonalen Protein-Transport, Vorwiegen der Glykogensynthese in den Nervenfaserendformationen. Allerdings fanden sich im ZNS von Branchiostoma niedrigere Stoffwechselraten als im ZNS von Brachydanio.
Comparative histophysiological investigations of different organs in Branchiostoma lanceolatum (Cephalochordata) and Brachydanio rerio (Teleostei)
Summary Incorporation of 3H-uridine, 3H-histidine and 3H-glucose into some organs (epidermis, CNS, muscles, spinal cord, notochord, liver, gills, intestine) of Branchiostoma lanceolatum (Acrania) and Brachydanio rerio (Teleostei) was investigated by means of comparative autoradiograms following incorporation periods of 11 min to 7 days. The metabolism of the labeled substances in the various homologous organs examined was quite similar, although it was 4 to 5 times higher in Branchiostoma than in Brachydanio; in the latter there was also a delay of tracer incorporation of about 3 hrs, a so-called lag-phase. In particular the metabolism of the CNS of Branchiostoma showed the same characteristics as the CNS of vertebrates, e. g. storage of neuronally synthesized RNA in the neuronal perikarya, axonal flow of proteins, glycogen synthesis in nerve endings. However, metabolic activity of the CNS was lower in Branchiostoma.
Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.  相似文献   
9.
Summary A double immunofluorescence method was devised to localize simultaneously urotensin-I (UI) and -II (UII) immunoreactivities in the caudal neurosecretory system of the goby, Gillichthys mirabilis. In a sequential fashion, sections of the posterior spinal cord and urophysis were treated with antiserum to corticotropin-releasing factor (CRF) that cross-reacts with UI, fluorescein-conjugated sheep anti-rabbit IgG, biotinylated anti-UII and rhodamine-conjugated avidin. UI and UII immunoreactivities appeared to coexist in some neurons and in most fibers and urophysial tissue; the remainder of the fibers and urophysis and the majority of neurons were immunoreactive for CRF/ UI only. No convincing evidence of immunoreactivity for UII only was found. A few nonreactive cells were seen, but these may not be neurosecretory neurons. The two immunoreactive cell types were not segregated topographically, and the intensity of perikaryal immunofluorescence for CRF/UI was variable. To explain these results a hypothesis that all caudal neurosecretory cells may synthesize both UI and UII and that immunoreactive differences may reflect different states of cellular activity, is suggested. This sequential double immunofluorescence method offers several advantages over other techniques and is especially useful for co-localization studies when primary antisera from different species are not available.  相似文献   
10.
Summary In the testis of Esox lucius at the time of spermiation, activity of cyclic adenosine 3,5-monophosphate (cAMP) was immunocytochemically localized at the level of the Sertoli cells. In these cells adenylate cyclase activity was also ultracytochemically demonstrated by using adenylyl imidodiphosphate as a substrate. Reaction products of adenylate cyclase were primarily detectable on the basal and adluminal plasma membranes and on the surface of protrusions of the cell body into the lumen.  相似文献   
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