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Pineal complex of the clawed toad, Xenopus laevis Daud.: structure and function.
Korf HW
,
Liesner R
,
Meissl H
,
Kirk A
.
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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) approximately 100 AChE-positive neurons, (iii) complex neuropil areas, and (iv) a pineal tract formed by approximately 10 myelinated and approximately 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.
BAGNARA,
PINEAL REGULATION OF BODY BLANCHING IN AMPHIBIAN LARVAE.
1965, Pubmed
BAGNARA,
PINEAL REGULATION OF BODY BLANCHING IN AMPHIBIAN LARVAE.
1965,
Pubmed
BAGNARA,
INDEPENDENT ACTIONS OF PINEAL AND HYPOPHYSIS IN THE REGULATION OF CHROMATOPHORES OF ANURAN LARVAE.
1964,
Pubmed
Bayrhuber,
[The forms of synapses and the occurrence of acetylcholinesterase in the pineal organ of Bombina variegata (L.), (Anura)].
1972,
Pubmed
DARTNALL,
The interpretation of spectral sensitivity curves.
1953,
Pubmed
DARTNALL,
Further observations on the visual pigments of the clawed toad, Xenopus laevis.
1956,
Pubmed
,
Xenbase
DENTON,
The visual sensitivity of the toad Xenopus laevis.
1954,
Pubmed
,
Xenbase
DODT,
[Reversible reversal of light sensitive systems in plants and animals].
1963,
Pubmed
DODT,
Mode of action of pineal nerve fibers in frogs.
1962,
Pubmed
DODT,
PHOTOSENSITIVITY OF A LOCALIZED REGION OF THE FROG DIENCEPHALON.
1963,
Pubmed
Diederen,
A possible functional relationship between the subcommissural organ and the pineal complex and lateral eyes in Rana esculenta and Rana temporaria.
1975,
Pubmed
Dodt,
[Purkinje shift, absolute threshold and adaptive behavior of single elements of the anuran intracranial epiphysis].
1964,
Pubmed
Donley,
Characteristics of slow potentials from the frog epiphysis (Rana esculenta); possible mass photoreceptor potentials.
1979,
Pubmed
Eakin,
PHOTORECEPTORS IN THE AMPHIBIAN FRONTAL ORGAN.
1961,
Pubmed
Eldred,
Central projections of the frontal organ of Rana pipiens, as demonstrated by the anterograde transport of horseradish peroxidase.
1980,
Pubmed
Eldred,
Pineal photoreceptors: evidence for a vertebrate visual pigment with two physiologically active states.
1978,
Pubmed
Hamasaki,
Interaction of excitation and inhibition in the stirnorgan of the frog.
1970,
Pubmed
Hartwig,
Letter: Evidence for photosensitive pigments in the pineal complex of the frog.
1974,
Pubmed
KARNOVSKY,
A "DIRECT-COLORING" THIOCHOLINE METHOD FOR CHOLINESTERASES.
1964,
Pubmed
Korf,
Histological, histochemical and electron microscopical studies on the nervous apparatus of the pineal organ in the tiger salamander, Ambystoma tigrinum.
1976,
Pubmed
Meissl,
Change of threshold after light-adaptation of the chromatic response of the frog's pineal organ (Stirnorgan).
1980,
Pubmed
Morita,
Nervous activity of the frog's epiphysis cerebri in relation to illumination.
1965,
Pubmed
OKSCHE,
[Electron microscope studies on the frontal organ of Anura. (On the problem of light receptors)].
1963,
Pubmed
Oksche,
[Electron microscopic studies on the nerve tracts of the pineal complex of Rana esculenta L].
1965,
Pubmed
Omura,
Responses of pineal photoreceptors in the brook and rainbow trout.
1980,
Pubmed
Paul,
[Neurons and central nervous connections of the pineal organ in Anura].
1971,
Pubmed
Ueck,
[Ultrastructure of the pineal sensory apparatus in some Pipidae and Discoglossidae].
1968,
Pubmed
Ueck,
Innervation of the vertebrate pineal.
1979,
Pubmed
Wake,
Acetylcholinesterase-containing nerve cells in the pineal complex and subcommissural area of the frogs, Rana ridibunda and Rana esculenta.
1974,
Pubmed
