Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 10 de 10
Filter
Add more filters










Publication year range
1.
J Comp Neurol ; 433(3): 401-14, 2001 May 07.
Article in English | MEDLINE | ID: mdl-11298364

ABSTRACT

Using light- and electron microscopic methods, we describe two novel putative extraocular photoreceptor organs in the optic lobes of the cockroaches Leucophaea maderae and Blaberus craniifer. The lamina organ is an elongated structure distal to the first optic chiasm, adjacent to the anterior edge of the lamina. The lobula organ is situated on the anterior distal surface of the lobula. In cross sections through the pigment-free organs, cell bodies are arranged in a closed or open circle and are interconnected by desmosomes. They send protrusions with rhabdom-like microvilli into a common, central space apparently filled with extracellular matrix. A different cell type gives rise to electron-dense lamellae, which also extend into the central space and partly join to form a common lamellar bundle. Axonal processes extend from the microvillar cells and run along the outer surface of the organs to the neighboring optic neuropils. The organs receive multiple efferent innervation from neurosecretory axons. Both organs show strong immunostaining with an antiserum against Arabidopsis cryptochrome 2 that is associated with the lamellated structure in the central lumen. The specific features of the organs suggest that they are homologous to similar organs in the optic lobe of beetles and may serve a role as extraocular photoreceptors for light entrainment of the circadian system.


Subject(s)
Cockroaches/physiology , Coleoptera/physiology , Photoreceptor Cells, Invertebrate/physiology , Animals , Cockroaches/anatomy & histology , Coleoptera/anatomy & histology , Microscopy, Electron , Photoreceptor Cells, Invertebrate/ultrastructure , Visual Pathways/anatomy & histology , Visual Pathways/cytology , Visual Pathways/physiology
2.
Biometals ; 13(4): 325-31, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11247039

ABSTRACT

Homing pigeons have been subject of various studies trying to detect magnetic material which might be involved in magnetic field perception. Here we focus on the upper-beak skin of homing pigeons, a region that has previously been shown to contain nerves sensitive to changes of the ambient magnetic field. We localized Fe3+ concentrations in the subcutis and identified the material by transmission electronmicroscopy (TEM) as aggregates of magnetite nanocrystals (with grain sizes between 1 and 5 nm). The particles form clusters of 1-3 microm diameter, which are arranged in distinct coherent elongated structures, associated with nervous tissue and located between fat cells. Complementary low-temperature magnetic measurements confirm the microscopic observations of fine-grained superparamagnetic particles in the tissue. Neither electron-microscopic nor magnetic measurements revealed any single-domain magnetite in the upper-beak skin tissue.


Subject(s)
Columbidae/metabolism , Iron/metabolism , Oxides/metabolism , Animals , Cold Temperature , Ferrosoferric Oxide , Homing Behavior , Magnetics , Microscopy, Electron
3.
Cell Tissue Res ; 286(3): 411-29, 1996 Dec.
Article in English | MEDLINE | ID: mdl-8929344

ABSTRACT

Central nervous system ganglia within the head of the beetle Pachymorpha sexguttata were labeled using an antibody that recognizes an evolutionarily conserved region of the period (per) gene product of Drosophila melanogaster. per and the protein it encodes (PER) are believed to play a central role in the generation of endogenous circadian rhythms in flies; therefore anti-PER-mediated immunoreactivity may help to uncover cellular components of the circadian clock system in that insect and in others. In the beetle, application of this antibody led to the staining of a distinct set of neurons located in the optic lobes and the central brain, plus small numbers of putative glial cells in the optic lobes. Neuronal perikarya (including their nuclei in a few cases), the axons, and terminal regions of the neurons were stained. The network formed by these labeled cells and processes are candidates for the neuronal basis of the beetle's circadian clock system: the pacemaker region situated next to the medulla neuropil, its connection to the apparent site of Zeitgeber input, and putative efferent pathways projecting to control centers of various effector systems. Anti-PER-mediated labeling and that resulting from application to beetle specimens of an antiserum against pigment-dispersing hormone (PDH) were compared; in the Drosophila brain all "PDH cells" express the per gene as well. In the beetle, however, the set of "PER cells" and PDH ones is at least in part nonoverlapping. The hypothesis that neurons stained by application of anti-PER participate in the control of the beetle's circadian rhythms is discussed in the context of previous electrophysiological and immunohistochemical studies. Also considered are analogies to, and differences from, labeling of the PER protein in fruit flies and PER-like immunoreactivity in other animals.


Subject(s)
Brain/metabolism , Coleoptera/metabolism , Ganglia, Invertebrate/metabolism , Neurons/metabolism , Nuclear Proteins/metabolism , Animals , Antibodies/metabolism , Brain/ultrastructure , Central Nervous System/metabolism , Circadian Rhythm , Drosophila Proteins , Drosophila melanogaster/metabolism , Esophagus/innervation , Female , Ganglia, Invertebrate/ultrastructure , Insect Hormones/metabolism , Male , Neurons/cytology , Optic Lobe, Nonmammalian/metabolism , Peptides/metabolism , Period Circadian Proteins , Rabbits , Staining and Labeling
4.
Cell Tissue Res ; 273(3): 435-45, 1993 Sep.
Article in English | MEDLINE | ID: mdl-8402826

ABSTRACT

A putative photoreceptor organ is described in the carabid beetle, Pachymorpha sexguttata. The elongated structure, about 20-40 microns wide and more than 300 microns long, is situated within the optic lobe at the fronto-dorsal rim of the lamina. It lies, deep in the head capsule, in front of the compound eyes and beneath window-like thinnings of the cuticle. The organ is composed of two types of cells: (1) clear sheath cells and (2) well-organized inner receptor cells that appear in a horseshoe-like or circular array in cross-section. Common histological features of all inner cells include a distal trunk ending in microvilli that form a rhabdom-like structure, an axon at the proximal end of the cell, lamellar and multivesicular bodies within the trunk, and clusters of small mitochondria. The organ has no shielding pigment. It is connected by thin axons to a circumscribed neuropil that parallels the organ, and thence via a fiber tract to the medulla accessoria, a possible site of the circadian pacemaker in insects. Immunoreactivity to anti-per(s), an antibody recognizing the Drosophila period (per) protein that plays a central role in the function of the circadian pacemaker in fruit flies, is demonstratable in thin efferent terminals within the organ, in the associated neuropil and in its fiber connection to the medulla. A second receptor organ displaying the same fine structure lies near the second optic chiasm. This set of putative photoreceptors also occurs in the tenebrionid beetle, Zophobas morio, and its pupa. The possible function of these receptor organs is discussed with respect to former chronobiological data and some recently described types of extraretinal photoreceptors in arthropods.


Subject(s)
Coleoptera/ultrastructure , Optic Lobe, Nonmammalian/ultrastructure , Photoreceptor Cells, Invertebrate/ultrastructure , Animals , Circadian Rhythm , Coleoptera/physiology , Light , Microscopy, Electron , Optic Lobe, Nonmammalian/physiology , Photoreceptor Cells, Invertebrate/physiology , Photoreceptor Cells, Invertebrate/radiation effects
5.
Cell Tissue Res ; 224(1): 233-8, 1982.
Article in English | MEDLINE | ID: mdl-6178512

ABSTRACT

The somata of the efferent neurosecretory fibers that control the circadian sensitivity rhythm in the median eyes of the scorpion, Androctonus australis, were detected in the brain by retrograde labeling with Lucifer Yellow CH. A total of 20-40 neurons are arranged in two groups displaying a bilaterally symmetrical, marginal position near the circumesophageal connectives. Half the cells in each group send fibers into the ipsilateral optic nerve; the fibers from the other half enter the contralateral optic nerve.


Subject(s)
Circadian Rhythm , Neurosecretory Systems/cytology , Scorpions/cytology , Animals , Isoquinolines , Nerve Fibers/ultrastructure , Optic Nerve/cytology , Scorpions/physiology , Staining and Labeling , Visual Pathways
6.
Cell Tissue Res ; 206(1): 95-104, 1980.
Article in English | MEDLINE | ID: mdl-7357598

ABSTRACT

The dioptric apparatus of the lateral eyes of the scorpion, Androctonus australis, consists of a cuticular lens, but lacks a vitreous body. The retina is formed by (1) retinula cells displaying a contiguous network of rhabdoms; (2) arhabdomeric cells bearing a distal dendrite that contacts retinula cells via numerous projections and ends before the rhabdomere of the retinula cells; (3) pigment cells that ensheath retinula and arhabdomeric cells with the exception of the contact regions; and (4) neurosecretory fibres possibly originating in the supraesophageal ganglion. The ratio of the number of retinula to arhabdomeric cells is determined to be close to 2:1 in the three larger anterolateral eyes, in contrast to the median eyes where the ratio is 5:1. The construction of the dioptric apparatus as well as the anatomy of the retina imply that in the lateral eyes of Androctonus australis visual acuity is reduced. A certain degree of spatial discrimination, however, may be retained by the presence of a relatively high number of arhabdomeric cells. It is suggested that the lateral eyes of A. australis mainly function as light detectors, e.g., for Zeitgeber stimuli.


Subject(s)
Scorpions/ultrastructure , Animals , Cell Nucleus/ultrastructure , Cytoplasmic Granules/ultrastructure , Eye/ultrastructure , Microvilli/ultrastructure , Neurosecretory Systems/ultrastructure , Organoids/ultrastructure , Retina/ultrastructure , Retinal Pigments
9.
Cell Tissue Res ; 178(2): 189-98, 1977 Mar 09.
Article in English | MEDLINE | ID: mdl-844075

ABSTRACT

The retina of the median eyes of the North African scorpion, Androctonus australis L., is supplied with numerous neurosecretory nerve fibres which establish synaptoid contacts on the retinula cells. The number of fibres or profiles of varicosities of fibre terminals associated with a retinular unit (five retinula cells with a fused rhabdom) varies between 10 and 20. Electron-opaque vesicles with a diameter of 80-100 nm are abundant within the axonal profiles. The synaptoid junctions are characterized by postsynaptic electron-dense material on the inner leaflet of the retinula cell membrane and, frequently, presynaptic submembranous dense material. Because of these ultrastructural features, the junctions observed here resemble typical interneuronal synaptic contacts. Hence this kind of neurosecretory junction appears to be unique among arthropods. It is suggested that the neurosecretory fibres within the retina represent the efferent pathways for the control of the circadian pigment movements within the retinula cells.


Subject(s)
Neurosecretory Systems/ultrastructure , Retina/ultrastructure , Scorpions/ultrastructure , Animals , Microscopy, Electron , Synapses/ultrastructure
SELECTION OF CITATIONS
SEARCH DETAIL
...