Golgi and Electron-Microscopic Golgi-GABA Immunostaining Study of the Avian Optic Tectum

1998 ◽  
Vol 162 (4) ◽  
pp. 209-225 ◽  
Author(s):  
T. Tömböl
Keyword(s):  
Optic Tectum ◽  
Electron Microscopic ◽  
Gaba Immunostaining

Anatomical mapping of retino-tectal connections in developing and metamorphosed Xenopus: evidence for changing connections

Development ◽  
1978 ◽  
Vol 45 (1) ◽  
pp. 249-270
Author(s):  
Alison Longley
Keyword(s):  
Optic Tectum ◽  
Wallerian Degeneration ◽  
Caudal Part ◽  
Electron Microscopic ◽  
Neural Connections ◽  
Retinal Axons ◽  
Retinal Lesion ◽  
Adult Pattern ◽  
Experimental Degeneration ◽  
Rostral Part

Neural connections between the eye and optic tectum in Xenopus laevis were anatomically traced by observing the tectal location of Wallerian degeneration after discrete retinal lesion. These retinotectal connections were mapped in postmetamorphic frogs and tadpoles at stage 51, the stage at which retinal axons have grown into about the rostral one-half of the tectum. The course of the experimental degeneration was the same in frogs and tadpoles, but degeneration proceeded faster in the younger animals. In the frogs, connections were ordered, with nasal retina mapping to the caudal part of the tectum and temporal retina mapping to the rostral tectum. In the tadpoles, within the innervated area at the rostral tectum, the retino-tectal connections were generally organized as in the adults, with the temporal retina mapping to the rostral part of the innervated tectum and nasal retina mapping primarily to the caudal part. But a portion of the nasal fibers consistently mapped to the far rostral tectum as well. Electron microscopic observations showed degenerating synaptic terminals at both rostral and caudal portions of the innervated tectum after lesion of just the nasal retina. Degeneration was not seen in control animals. These results indicate that some fibers (particularly from nasal retina) may shift their terminals caudally on the tectum to match tectal growth and produce the adult pattern of connections. If there is such connection readjustment, the ‘aberrant’ connections from nasal retina in tadpoles may be an indication of this process.

A light- and electron-microscopic investigation of the optic tectum of the frog, Rana pipiens, II: The neurons that give rise to the crossed tecto-bulbar pathway

1990 ◽  
Vol 4 (6) ◽  
pp. 519-531 ◽  
Author(s):  
Thomas E. Hughes
Keyword(s):  
Optic Tectum ◽  
Ganglion Cells ◽  
Retrograde Transport ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Retinal Ganglion ◽  
Electron Microscopic ◽  
Retinal Axons ◽  
Tectal Neurons ◽  
Apical Dendrites

AbstractThe superficial layers of the frog's optic tectum, Potter's (1969) layers A-G, comprise a complex neuropil made up of many afferent axons, the somata of a few neurons, and many dendrites from the neurons located in the deeper layers. Different types of retinal axons are believed to terminate in different layers (Maturana et al., 1960; Kuljis & Karten, 1988; Sargent et al., 1989), but little is known about the relationships between each type of input and the dendrites of the deep tectal neurons that extend into these superficial layers. The present study used the method of retrograde transport of horseradish peroxidase to study the synaptic contacts on the dendrites of the neurons that give rise to the crossed tecto-bulbar pathway. These cells have apical dendrites that ascend through the superficial retino-recipient layers.The somata of the cells that give rise to the crossed tecto-bulbar pathway are located in the superficial half of layer 6, preferentially clustered along the caudal, lateral, and rostral margins of the tectum. The somata of these cells range from 8−30 ¼m in diameter. Their axons are large (2−4 ¼m in diameter) myelinated fibers that arise from either their somata or proximal dendrites. Their axons travel within the deep medullary layer to leave the tectum at the lateral margin. Their dendritic arbors extend obliquely through the superficial layers to reach layer B where they turn and extend within the layer for up to 0.5 mm. The somata of these cells receive only a scant synaptic input. In contrast, their dendrites receive input in every layer, but the nature of this input varies from layer to layer. Synaptic terminals that resemble retinal ganglion cell boutons contact the labeled dendrites in layers B, F, and G. This indicates that the dendrites may receive monosynaptic input from several types of retinal ganglion cells. Terminals with small, flattened vesicles also contact the dendrites of these cells in each layer. In layer F and below, the terminals with flattened vesicles constitute 15% of the contacts; above layer F they constitute only 5−8% of the contacts. Terminals with medium-sized, flattened vesicles also contact the dendrites of these cells in every layer and constitute a large proportion of their input (33−95%). The latter terminals resemble those that are often postsynaptic to retinal terminals.

A light- and electron-microscopic investigation of the optic tectum of the frog, Rana pipiens, I: The retinal axons

1990 ◽  
Vol 4 (6) ◽  
pp. 499-518 ◽  
Author(s):  
Thomas E. Hughes
Keyword(s):  
Optic Tectum ◽  
Rana Pipiens ◽  
Ganglion Cells ◽  
Light And Electron Microscopy ◽  
Distribution Patterns ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Layer By Layer ◽  
Electron Microscopic ◽  
Retinal Axons

AbstractThere are several different groups of ganglion cells in the retina of the frog. Although their axons are thought to terminate in different layers of the optic tectum, little is known about the morphology of their terminal arbors or their synaptic targets. The present paper reports the results of a layer-by-layer study of horseradish peroxidase labeled retinal axons in the optic tectum of Rana pipiens. Light and electron microscopy was used to study the axon's laminar distribution, patterns of arborization, and synaptic contacts.Labeled retinal axons were found in all of the superficial layers of the tectum (A-G). From layer to layer, the retinal axons differed markedly in the diameter of their parent axons (0.2−3.0 μm) and in the morphology and horizontal extent of their terminal arbors.Five classes of synaptic terminals could be distinguished in the tectum. The retinal terminals belonged to class characterized by round, medium-sized synaptic vesicles. They made synaptic contact with dendrites and other axon terminals in each of the layers. They were always the presynaptic component. The postsynaptic dendrites were often the vertically oriented processes of cells located in the deeper layers. The postsynaptic terminals belonged to a class distinguished by their flat, medium-sized vesicles. These terminals in turn contacted what appeared to be dendrites. In layer eight, the retinal axons were often large, spoon-shaped boutons that ended in apposition with the somata of the layer.

A Reproducible Selective Stain for Cardiac Sarcoplasmic Reticulum

1974 ◽  
Vol 32 ◽  
pp. 214-215
Author(s):  
R. A. Waugh ◽  
J. R. Sommer
Keyword(s):  
Complex System ◽  
Electron Microscope ◽  
Sarcoplasmic Reticulum ◽  
Transmission Electron Microscope ◽  
Electron Microscopic ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Transmission Electron

Cardiac sarcoplasmic reticulum (SR) is a complex system of intracellular tubules that, due to their small size and juxtaposition to such electron-dense structures as mitochondria and myofibrils, are often inconspicuous in conventionally prepared electron microscopic material. This study reports a method with which the SR is selectively “stained” which facilitates visualizationwith the transmission electron microscope.

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