scholarly journals Distribution and structure of efferent synapses in the chicken retina

2009 ◽  
Vol 26 (2) ◽  
pp. 215-226 ◽  
Author(s):  
S. H. LINDSTROM ◽  
N. NACSA ◽  
T. BLANKENSHIP ◽  
P. G. FITZGERALD ◽  
C. WELLER ◽  
...  
Keyword(s):  
Amacrine Cell ◽  
Retinal Neurons ◽  
Transmission Electron ◽  
Efferent Projection ◽  
Cell Processes ◽  
Chicken Retina ◽  
Synaptic Structures ◽  
To Receive ◽  
Dorsal Retina ◽  
Anterograde Labeling

AbstractThe visual system of birds includes an efferent projection from a visual area, the isthmo-optic nucleus in the midbrain, back to the retina. Using a combination of anterograde labeling of efferent fibers, reconstruction of dye-filled neurons, NADPH-diaphorase staining, and transmission electron microscopy, we have examined the distribution of efferent fibers and their synaptic structures in the chicken retina. We show that efferent fibers terminate strictly within the ventral retina. In two completely mapped retinas, only 2 fibers from a total of 15,359 terminated in the dorsal retina. The major synapse made by each efferent fiber is with a single efferent target amacrine cell (TC). This synapse consists of 5–25 boutons of 2 μm diameter, each with multiple active zones, pressed into the TC soma or synapsing with a basketwork of rudimentary TC dendrites in the inner nuclear layer (INL). This basketwork, which is sheathed by Muller cell processes, defines a private neuropil in the INL within which TCs were also seen to receive input from retinal neurons. In addition to the major synapse, efferent fibers typically produce several very thin processes that terminate nearby in single small boutons and for which the soma of a local amacrine cell is one of the likely postsynaptic partners. A minority of efferent fibers also give rise to a thicker process, terminating in a strongly diaphorase-positive ball about 5 μm in diameter.

Immunolocalization of metabotropic glutamate receptors 1 and 5 in the synaptic layers of the chicken retina

2006 ◽  
Vol 23 (2) ◽  
pp. 221-231 ◽  
Author(s):  
MADHUMITA SEN ◽  
EVANNA GLEASON
Keyword(s):  
Glutamate Receptors ◽  
Bipolar Cell ◽  
Metabotropic Glutamate Receptors ◽  
Amacrine Cell ◽  
Plexiform Layer ◽  
Inner Plexiform Layer ◽  
Double Labeling ◽  
Metabotropic Glutamate ◽  
Cell Processes ◽  
Chicken Retina

We have examined the distribution of metabotropic glutamate receptors (mGluRs) 1 and 5 in the adult chicken retina using preembedding immuno-electronmicroscopy. Immunoreactivity for mGluRs 1 and 5 was found in both the outer plexiform layer (OPL) and the inner plexiform layer (IPL). For mGluR1, OPL labeling was observed at cone pedicles and horizontal and bipolar cell processes. In the IPL, mGluR1 labeling could be found on bipolar cell terminals, as well as postsynaptic processes, including amacrine cell processes. Neither presynaptic nor postsynaptic elements were labeled at rod synapses. For mGluR5, OPL labeling was associated with cone pedicles as well as bipolar and horizontal cell processes. As for mGluR1, rod synapses were unlabeled. In the IPL, labeling for mGluR5 was found on bipolar cell terminals and amacrine cell processes. The presynaptic expression of these receptors in the OPL was confirmed at the light level by double-labeling experiments with SV2. The distributions of mGluRs 1 and 5 indicate that they have the potential to regulate function in both synaptic layers. Furthermore, the similar expression patterns for these two receptors indicate that they might be co-expressed and thus have the potential to interact functionally.

scholarly journals The principal neurons of the medial nucleus of the trapezoid body and NG2+ glial cells receive coordinated excitatory synaptic input

2009 ◽  
Vol 134 (2) ◽  
pp. 115-127 ◽  
Author(s):  
Jochen Müller ◽  
Daniel Reyes-Haro ◽  
Tatjyana Pivneva ◽  
Christiane Nolte ◽  
Roland Schaette ◽  
...  
Keyword(s):  
Glial Cell ◽  
Glial Cells ◽  
Synaptic Input ◽  
Medial Nucleus ◽  
Synaptic Structure ◽  
Excitatory Synaptic Input ◽  
Cell Processes ◽  
To Receive ◽  
Trapezoid Body ◽  
Axosomatic Synapse

Glial cell processes are part of the synaptic structure and sense spillover of transmitter, while some glial cells can even receive direct synaptic input. Here, we report that a defined type of glial cell in the medial nucleus of the trapezoid body (MNTB) receives excitatory glutamatergic synaptic input from the calyx of Held (CoH). This giant glutamatergic terminal forms an axosomatic synapse with a single principal neuron located in the MNTB. The NG2 glia, as postsynaptic principal neurons, establish synapse-like structures with the CoH terminal. In contrast to the principal neurons, which are known to receive excitatory as well as inhibitory inputs, the NG2 glia receive mostly, if not exclusively, α-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid receptor–mediated evoked and spontaneous synaptic input. Simultaneous recordings from neurons and NG2 glia indicate that they partially receive synchronized spontaneous input. This shows that an NG2+ glial cell and a postsynaptic neuron share presynaptic terminals.

Synaptic connections involving immunoreactive glycine receptors in the turtle retina

1993 ◽  
Vol 10 (5) ◽  
pp. 907-914 ◽  
Author(s):  
Charles L. Zucker ◽  
Berndt Ehinger
Keyword(s):  
Amacrine Cell ◽  
Ganglion Cells ◽  
Glycine Receptor ◽  
Plexiform Layer ◽  
Photoreceptor Cells ◽  
Bimodal Distribution ◽  
Inner Nuclear Layer ◽  
Inner Plexiform Layer ◽  
Glycine Receptors ◽  
Cell Processes

AbstractThe distribution of glycine receptors in the turtle retina was studied with the aid of a monoclonal antibody that detects the 93-kD protein associated with the strychnine-sensitive glycine receptor. Light microscopically, receptors were found in the inner plexiform layer and, more sparsely, in the innermost parts of the inner nuclear layer. No receptors were seen to be associated with photoreceptor cells, horizontal cells, or any other structures in the distal inner nuclear layer or outer plexiform layer. Ultrastructurally, glycine receptors were found on the inner face of postsynaptic membranes of processes from amacrine and presumed ganglion cells and always involved amacrine cell processes as the presynaptic element. Such glycine receptor immunoreactive synapses onto amacrine cell processes were distributed throughout the inner plexiform layer with a peak density near the middle. On the other hand, output synapses onto ganglion cell processes displaying immunoreactive glycine receptor sites showed a bimodal distribution in the inner plexiform layer. Glycine receptor immunoreactivity was not detected on bipolar cells, but presumed glycine-utilizing processes (i.e. those presynaptic to immunoreactive glycine receptors) were occasionally found to be postsynaptic in bipolar cell dyads. The majority of the synaptic input to the presumed glycine-utilizing amacrine cell processes was from other amacrine processes, some of which were themselves glycine utilizing. The observations suggest that glycinergic synapses in the turtle retina are, to a large extent, engaged in processing interamacrine signals.

Cellular organization and fine structure of type II microtrich sensilla in gammaridean amphipods (Crustacea)

1999 ◽  
Vol 77 (1) ◽  
pp. 88-107 ◽  
Author(s):  
V J Steele ◽  
D H Steele
Keyword(s):  
Sensory Neurons ◽  
Sensory Cell ◽  
Cell Process ◽  
Outer Cell ◽  
Type Ii ◽  
Cellular Organization ◽  
Insect Sensilla ◽  
Transmission Electron ◽  
Cell Processes ◽  
Tormogen Cell

The cellular organization of type II microtrich sensilla was studied in male Anonyx lilljeborgi Boeck, 1871 (Lysianassoidea) by light and transmission electron microscopy. The sensillum consists of two bipolar sensory neurons and three concentric sheath cells. The sensory cell bodies are subepidermal. In each sensillum both dendrites are enclosed by the thecogen cell process. The inner dendritic segments are filled with mitochondria and lucent vesicles and expand in the epidermis into a spindle-shaped swelling. One of the neurons gives rise to two cilia and the second to a single cilium. These three outer dendritic segments lie in the receptorlymph cavity. The dendritic sheath, secreted by the thecogen cell process, completely ensheaths the outer dendritic segments. The trichogen (middle) cell and the tormogen (outer) cell incompletely enclose the thecogen cell, but their processes form autojunctions around the dendritic sheath in the apical epidermis. In premolt, the trichogen cell processes project into the exuvial space. The cytoplasm of the tormogen cell and the bordering epidermal cells contains coarse osmiophilic inclusions. All the cells of the sensillum are joined by desmosomes. The sensilla structurally resemble chemosensory (gustatory) insect sensilla.

Characterization of mammary cells from the lactating rat by electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 560-561
Author(s):  
P. Sadhukhan ◽  
J. Chakraborty ◽  
M. S. Soloff ◽  
M. H. Wieder ◽  
D. Senitzer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Types ◽  
Myoepithelial Cells ◽  
Mammary Tissue ◽  
Secretory Cells ◽  
Isolated Cells ◽  
Transmission Electron ◽  
Cell Processes ◽  
Phosphatase Cytochemistry

The means to identify cells isolated from the mammary gland of the lactating rat as a prerequisite for cell purification have been developed.The cells were isolated from mammary tissue with 0. 1% collagenase, and they were visualized by scanning and transmission electron microscopy and by alkaline phosphatase cytochemistry.The milk-secreting cells have surface microvilli, whereas the surface of the myoepithelial cells is smooth (Fig. 1). The two isolated epithelial cell types are readily distinguishable by transmission electron microscopy (Fig. 2). The secretory cells contain vacuoles and a relatively extensive rough endoplasmic reticulum, whereas the myoepithelial cells contain a more osmiophilic cytoplasm, contractile filaments (Fig. 3) and elongate processes. These features are consistent with the appearance of the two cell types in situ.Incubation of isolated cells with oxytocin prior to glutaraldehyde fixation resulted in the contraction of the myoepithelial cell processes (Figs. 4 & 5). This physiological response to oxytocin shows that the isolated myoepithelial cells were intact. The appearance of isolated secretory cells was unchanged by the presence of oxytocin.

Identification and distribution of gap junctions in the mesoderm of the developing chick limb bud

Development ◽  
1978 ◽  
Vol 46 (1) ◽  
pp. 99-110
Author(s):  
Robert O. Kelley ◽  
John F. Fallon
Keyword(s):  
Electron Microscopy ◽  
Gap Junctions ◽  
Limb Development ◽  
Freeze Fracture ◽  
Mesenchymal Cells ◽  
Limb Bud ◽  
Metabolic Coupling ◽  
Transmission Electron ◽  
Communicating Junctions ◽  
Cell Processes

Sub-ridge, core, anterior and posterior borders of mesoderm were dissected from stages 22–24 chick wing buds to investigate whether structures for intercellular coupling develop between mesenchymal cells. Fine structure was examined using techniques of transmission electron microscopy, freeze-fracture and scanning electron microscopy. Gap (communicating) junctions which were observed between mesenchymal cells of all limb bud regions were distributed between apposed cell bodies, points of contact between cell processes and other cell bodies, and between contacting tips of slender cell projections. In addition, particularly in the subridge region, filopodia were observed to extend through the intercellular matrix to contact other cells several micrometers distant. The observations reported in this paper show that mesodermal cells throughout the limb have the structural capability for electrotonic and metabolic coupling during a critical period of morphogensisis in the avian limb. Whether intercellular signals which are thought to be transmitted through gap junctions are active in normal limb development remains to be investigated.

Disruption of transient photoreceptor targeting within the inner plexiform layer following early ablation of cholinergic amacrine cells in the ferret

2001 ◽  
Vol 18 (5) ◽  
pp. 741-751 ◽  
Author(s):  
P.T. JOHNSON ◽  
M.A. RAVEN ◽  
B.E. REESE
Keyword(s):  
Retinal Ganglion Cells ◽  
Amacrine Cell ◽  
Ganglion Cells ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Inner Plexiform Layer ◽  
Retinal Ganglion ◽  
Subcutaneous Injections ◽  
Cell Processes ◽  
Cholinergic Amacrine Cells

Photoreceptors in the ferret's retina have been shown to project transiently to the inner plexiform layer (IPL) prior to their differentiation of an outer segment. On postnatal day 15 (P-15), when this projection achieves maximal density, the photoreceptors projecting into the IPL extend primarily to one of two depths, coincident with the processes of cholinergic amacrine cells. The present study has used an excitotoxic approach employing subcutaneous injections of l-glutamate to ablate these cholinergic amacrine cells on P-7, in order to see whether their elimination alters this targeting of photoreceptor terminals within the IPL. The near-complete elimination of cholinergic amacrine cells at P-15 was confirmed, although the population of retinal ganglion cells was also affected, being depleted by roughly 50%. The rod opsin-immunopositive terminals in such treated ferrets no longer showed a stratified distribution, being found throughout the depth of the IPL, as well as extending into the ganglion cell layer. This effect should not be due to the partial loss of retinal ganglion cells, however, since optic nerve transection at P-2, which eliminates the ganglion cells entirely while leaving the cholinergic amacrine cell population intact, was shown not to affect the stratification pattern of the photoreceptors within the IPL. These results strongly suggest that the targeting of the photoreceptor terminals to discrete strata within the IPL is dependent upon the cholinergic amacrine cell processes.

Human neonatal hydrocephalus

1985 ◽  
Vol 63 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Marc R. Del Bigio ◽  
J. Edward Bruni ◽  
H. Derek Fewer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ependymal Cells ◽  
Foramen Of Monro ◽  
Content Type ◽  
Axonal Pathology ◽  
Transmission Electron ◽  
Cell Processes ◽  
Junctional Complexes ◽  
Fine Print

✓ An infant of 43 weeks gestational age with severe congenital hydrocephalus was operated on for removal of a subependymal astrocytoma in the region of the foramen of Monro. A biopsy of periventricular tissue was taken from the lateral ventricle for examination by scanning and transmission electron microscopy. The ependyma was largely denuded, with glial cell processes forming most of the ventricular lining. Many of the attenuated ependymal cells, however, had intact junctional complexes at areas of contact with other ependymal cells. Club-shaped unipolar cells, believed to be a previously undescribed form of immature ependymal cells, were found in the ventricular lining. Cerebrospinal fluid edema was present in the neuropil up to 60 µm from the ventricular lumen, but there was no obvious axonal pathology in the tissues examined.

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