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  • 1
    Electronic Resource
    Electronic Resource
    Pineal complex of the clawed toad, Xenopus laevis Daud.: Structure and function (1981)
    Springer
    Cell & tissue research 216 (1981), S. 113-130 
    Details
    ISSN: 1432-0878
    Keywords: Pineal complex ; AChE-positive neurons ; Plexiform areas ; Photosensory function ; Xenopus laevis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological and physiological properties of the pineal complex of Xenopus laevis were investigated in larval, juvenile and adult animals. In a representative majority of adult X. laevis, the frontal organ does not display signs of degeneration. Fully differentiated frontal organs contain photoreceptors typical of the pineal complex of lower vertebrates. By means of the acetylcholinesterase (AChE)-reaction approximately 30 neurons of two different types were demonstrated in the frontal organ. The frontal-organ nerve is composed of approximately 10 myelinated and 40 unmyelinated nerve fibers. The neuropil areas of the frontal organ are generally similar to the corresponding structures of the intracranial epiphysis. The neuronal apparatus of the epiphysis cerebri of X. laevis consists of (i) photoreceptor cells, (ii) ∼100 AChE-positive neurons, (iii) complex neuropil areas, and (iv) a pineal tract formed by ∼10 myelinated and ∼100 unmyelinated nerve fibers. Some of them exhibit granular inclusions indicating that pinealopetal elements may enter the pineal complex of X. laevis via this pathway. The topography of the pineal tract of X. laevis differs considerably from that in ranid species. The most conspicuous element of the plexiform zones is the ribbon synapse. The basal processes of the photoreceptor cells may be presynaptic elements of simple, tangential, dyad or triad synaptic contacts. Conventional synapses were observed only occasionally. Electrophysiological recordings revealed that the pineal complex of Xenopus laevis is directly sensitive to light. In response to light stimuli, two types of responses, achromatic and chromatic, were recorded from the nerve of the frontal organ. In contrast, the epiphysis exhibited only achromatic units. The opposed color mechanism of the chromatic response showed a maximum sensitivity at approximately 360 nm for the inhibitory and at 520 nm for the excitatory event. The action spectrum of the achromatic response of the epiphysis and the frontal organ peaked between 500 and 520 nm and showed no Purkinje-shift during dark adaptation. The functional significance of these phenomena is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234548
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  • 2
    Electronic Resource
    Electronic Resource
    Central innervation of the pineal organ of the Mongolian gerbil (1983)
    Springer
    Cell & tissue research 230 (1983), S. 259-272 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ, Mongolian gerbil ; Pinealopetal innervation ; Degeneration, synapses ; Habenular lesions ; Acetylcholinesterase-positive neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Nerve fibers connecting the brain with the pineal gland of the Mongolian gerbil (central pinealopetal fibers) were investigated by means of light and electron microscopy. Several myelinated fibers penetrate from the brain into the deep pineal gland, extend further into the pineal stalk and continue to the superficial portion of the pineal gland. In the centripetal direction these fibers were traced to the stria medullaris and to the habenular nuclei, where they turned laterad and then occupied a position immediately ventral to the optic tract. As shown in electron micrographs, lesions of the habenular area led to degeneration of myelinated fibers and nerve boutons in the deep pineal gland, the pineal stalk and the superficial pineal gland. Only boutons containing clear transmitter vesicles (devoid of a dense core) were observed to degenerate after the habenular lesions. On the other hand, removal of the superior cervical ganglia resulted in degeneration of boutons containing small (40 to 60 nm in diameter) dense-core vesicles. Several of the nerve fibers that penetrate into the deep pineal directly from the brain (central fibers) exhibited a positive reaction for acetylcholinesterase (AChE). AChE-positive perikarya were located in the projections of the stria medullaris, the lateral portions of the deep pineal, the area of the posterior commissure, and the periventricular gray of the mesencephalon. Such perikarya were found neither in the pineal stalk nor in the superficial pineal gland. These results present anatomical evidence that the pineal organ of the Mongolian gerbil receives multiple nervous inputs mediated by peripheral autonomic (i.e., sympathetic) nerve fibers, on the one hand, and by central fibers, on the other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213804
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  • 3
    Electronic Resource
    Electronic Resource
    The origin of central pinealopetal nerve fibers in the Mongolian gerbil as demonstrated by the retrograde transport of horseradish peroxidase (1983)
    Springer
    Cell & tissue research 230 (1983), S. 273-287 
    Details
    ISSN: 1432-0878
    Keywords: Pineal gland, Mongolian gerbil ; Central pinealopetal innervation ; Horseradish peroxidase ; Retrograde axonal transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The location of perikarya and nerve fibers projecting via the habenular and posterior commissures from the brain into the pineal organ of the Mongolian gerbil was investigated by the use of the retrograde horseradish peroxidase (HRP)-tracing method. After microiontophoretic or hydraulic injection of the tracer into the superficial pineal gland via a glass micropipette, and after survival periods of 6 to 48 h, the animals were transcardially perfused and the brains processed for the histochemical demonstration of the enzyme. In the pineal stalk 15 to 20 nerve fibers, including 4 to 7 myelinated elements, were traced back to the brain. HRP-labeled perikarya were located in the medial and lateral habenular nuclei as well as in the nucleus of the posterior commissure. Few fibers projected rostrally to perikarya in the paraventricular nucleus of the hypothalamus. A striking and persistent finding was the labeling of fibers that, in the habenular area, bent laterad and continued ventral to the optic tract. These fibers originated from perikarya located in the dorsal nucleus of the lateral geniculate body. These results strongly suggest a central innervation of the pineal organ in the Mongolian gerbil originating from hypothalamic and limbic areas of the brain as well as from the optic system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213805
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  • 4
    Electronic Resource
    Electronic Resource
    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) (1983)
    Springer
    Cell & tissue research 230 (1983), S. 289-307 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ ; Parapineal organ ; Opsin immunoreactivity ; Cyclostome (Lampetra fluviatilis) ; Teleosts (Anguilla anguilla, Salmo gairdneri)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213806
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  • 5
    Electronic Resource
    Electronic Resource
    Oxytocin-and vasopressin-immunoreactive nerve fibers in the pineal gland of the hedgehog, Erinaceus europaeus L. (1981)
    Springer
    Cell & tissue research 220 (1981), S. 87-97 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ, hedgehog ; Pinealopetal innervation ; Oxytocin ; Vasopressin ; Paraventricular nucleus ; Hibernation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Oxytocin-and vasopressin-immunoreactive nerve fibers, apparently originating from a dorsal subunit of the paraventricular nucleus, were demonstrated in the pineal gland of the hedgehog. The majority of these fibers (pinealopetal projections) is intimately related to the capillaries of the pineal organ, whereas only a few elements are scattered throughout the pineal parenchyma. The number of peptidergic elements observed in the central portion of the pineal organ exceeds that of fibers located at the periphery. In relation to the functional state of the animals, the amount of immunoreactive material in these pinealopetal nerve fibers exhibits conspicuous variations. In hibernating hedgehogs (group 1), these nerve fibers were considerably richer in oxytocin than in non-hibernating or arousing winter animals (group 2 and 3). In contrast, only weak immunoreactivity for vasopressin was found in intrapineal nerve fibers of hibernating hedgehogs (group 1), whereas the fibers of arousing or non-hibernating hedgehogs (group 2 and 3) contained slightly larger amounts of vasopressin. In the pineal organ of animals sacrificed during the summer period (group 4), no immunoreactivity for both neuropeptides was found. The functional significance of the connection between the hypothalamic paraventricular nucleus and the pineal organ is discussed with special reference to the vascular terminals of the pinealopetal peptidergic nerve fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209968
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  • 6
    Electronic Resource
    Electronic Resource
    CSF-contacting and other somatostatin-immunoreactive neurons in the brains of Anguilla anguilla, Phoxinus phoxinus, and Salmo gairdneri (Teleostei) (1983)
    Springer
    Cell & tissue research 233 (1983), S. 319-334 
    Details
    ISSN: 1432-0878
    Keywords: CSF-contacting neurons ; Somatostatin immunocytochemistry ; Hypothalamus ; Entopeduncular nucleus ; Pretectal area ; Tegmentum ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238299
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  • 7
    Electronic Resource
    Electronic Resource
    Distribution of sensory neurones of the pudendal nerve in the dorsal root ganglia and their projection to the spinal cord (1982)
    Springer
    Cell & tissue research 226 (1982), S. 555-564 
    Details
    ISSN: 1432-0878
    Keywords: Pudendal nerve ; Sensory neurones ; Spinal ganglion ; Transganglionic labelling (HRP) ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphology and distribution of the sensory neurones of the pudendal nerve within the spinal ganglia of rats were investigated by use of horseradish peroxidase (HRP). The labelling was visualized in diaminobenzidine (DAB) or tetramethyl-benzidine (TMB)-stained sections. Injection of HRP directly into the pudendal nerve labelled perikarya predominantly in the sixth lumbar DRG (L6). Following injection of HRP into the scrotal skin, however, additional cells were labelled in L5 and SI. Labelling was invariably unilateral. Approximately equal numbers of small (〈30 μm) and large neurones (〉40 μm) were labelled following subcutaneous injections although injections into the nerve marked twice as many small cells as large cells. This suggests that, in the rat, most of the small-diameter fibres within the pudendal nerve ascend through L6. Although a cluster of neurones was observed in one experiment, the remaining 25 experiments did not reveal any somatotopic arrangement since the labelled perikarya were distributed evenly throughout the ganglion. Similar numbers of retrogradely labelled neurones (somatopetal transport of the tracer) were observed in both DAB- and TMB-stained sections, although TMB allowed the demonstration of anterograde (somatofugal) HRP transport by terminal labelling in the superficial laminae of the lumbar spinal cord, extending into laminae II–IV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214784
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  • 8
    Electronic Resource
    Electronic Resource
    Nervous connections of the parietal eye in adult Lacerta s. sicula Rafinesque as demonstrated by anterograde and retrograde transport of horseradish peroxidase (1981)
    Springer
    Cell & tissue research 219 (1981), S. 567-583 
    Details
    ISSN: 1432-0878
    Keywords: Parietal eye (Lacertilia) ; Nervous connections ; Parietofugal projections ; Parietopetal projections ; Hypothalamic connections ; Lacerta s. sicula Rafinesque
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Subsequent to the injection of horseradish peroxidase into the parietal eye of adult Lacerta sicula, the course of the parietal nerve and its projections were determined. The parietal nerve enters the left habenular ganglion where it branches into a medial and a lateral route. Some nerve fibers decussate within the habenular commissure. Whereas this pathway exhibits a striking asymmetry at the level of the habenular ganglia, its projections to the dorsolateral nucleus of the thalamus, the periventricular hypothalamic area, the preoptic hypothalamic and telencephalic regions, and the pretectal area are arranged in a strictly symmetric manner. A possible innervation of tegmental areas could not be proven due to the presence of endogenous peroxidase within these regions. No parietal nerve fibers were observed in the optic tectum. In a few animals investigated, scattered labeled perikarya were located in the periventricular hypothalamic gray indicating a parietopetal innervation in Lacerta sicula. The injection of horseradish peroxidase into one of the lateral eyes revealed terminal areas of the optic nerve within the preoptic region, and the thalamic and pretectal nuclei, displaying partial overlapping with the projections of the parietal nerve to these areas. From the present investigation further evidence is obtained that the pineal complex of lower vertebrates is a component of the photoneuroendocrine system. Particular emphasis is placed upon the nervous connections between the parietal eye and the hypothalamus, described for the first time in the present study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209995
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  • 9
    Electronic Resource
    Electronic Resource
    Opsin-immunoreactive outer segments and acetylcholinesterase-positive neurons in the pineal complex of Phoxinus phoxinus (Teleostei, Cyprinidae) (1982)
    Springer
    Cell & tissue research 227 (1982), S. 351-369 
    Details
    ISSN: 1432-0878
    Keywords: Pineal photoreceptors ; Opsin immunoreactivity ; Pineal neurons ; Acetylcholinesterase reaction ; Parapineal organ ; Teleosts (Phoxinus phoxinus L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pineal complex of the teleost, Phoxinus phoxinus L., was studied light-microscopically by the use of the indirect immunocytochemical antiopsin reaction and the histochemical acetylcholinersterase (AChE) method. Opsin-immunoreactive outer segments of photoreceptor cells were demonstrated in large numbers in all divisions of the pineal end-vesicle and in the pineal stalk. Moreover, they were found in the roof of the third ventricle, adjacent to the orifice of the pineal recess as well as scattered in the parapineal organ. These immunocytochemical observations provide direct evidence of the presence of an opsin associated with a photopigment in the photosensory cells of the pineal and parapineal organs of Phoxinus. By means of the AChE reaction (Karnovsky and Roots 1964) inner segments of pineal photoreceptors, intrinsic nerve cells, several intrapineal bundles of nerve fibers, and a prominent pineal tract were specifically marked. The pineal neurons can be divided into two types: one is located near the pineal lumen, the other near the basal lamina. The latter perikarya bear stained processes directed toward the photoreceptor layer. A rostral aggregation of two types of AChE-positive nerve cells occurs in the ventral wall of the pineal end-vesicle. The main portion of the AChE-positive pineal tract, which lies within the dorsal wall of the pineal stalk, can be followed to the posterior commissure where some of the nerve fibers course laterally. A few AChE-positive pineal nerve fibers run toward the lateral habenular nucleus via the habenular commissure. In the region of the subcommissural organ single AChE-positive neurons accompany the pineal tract. The nerve cells of the parapineal organ exhibit a moderate AChE activity. These findings extend the structural basis for the remarkable light-dependent activity of the pineal organ of Phoxinus phoxinus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210891
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