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J Destombes

Publications and source records attributed to J Destombes.

26 records · Page 2Linked to original sources
PubMed1983

[Recent findings on the external oculomotor nucleus: the center for horizontal ocular movement].

Various neurobiological methods allowing the analysis of electrophysiological and morphological properties of a cell population within the central nervous system will be illustrated in the study of the abducens nucleus. Intracellular recordings provided the functional identification of the different types of cells within the abducens nucleus. Antidromic excitation, refractoriness, conduction velocity and frequency of discharges indicated the properties of the abducens motoneurones. Various types of afferent stimulations were applied to study the synaptic responses of the neurones. A dye was then electrophoretically injected and the labelled neurone observed with a light microscope. Full reconstruction of dendritic arborization and of axon trajectory was performed. The morphological study has shown the heterogeneity of the population of the motor nucleus, and the ultrastructural features indicated a complex synaptic organisation. The origin of some afferent terminals was determined.

Abducens Nerve↗
PubMed1981

Ultrastructural study of vestibular and reticular projections to the abducens nucleus.

The origin of the synaptic boutons in the abducens nucleus was studied following lesions of the contralateral medial vestibular nucleus, the ipsilateral paramedian pontine reticular formation and the contralateral dorsomedial part of the reticular formation caudal to the abducens nucleus. Lesions in the rostral part of the contralateral medial vestibular nucleus resulted in degeneration of boutons located mainly on dendritic processes. On the other hand, lesions in both ipsilateral and contralateral reticular formations provoked degenerating terminals on the somata of the abducens neurones and on proximal dendrites in the abducens nucleus beneath of genu of the facial nerve.

Abducens Nerve↗
PubMed1979

The fine structure of neurones and cellular relationships in the abducens nucleus in the cat.

Light and electron microscope studies of the abducens nucleus in the cat have disclosed two populations of neurones: large neurones 25 to 75 micrometer in diameter and small neurones 10 to 25 micrometer in diameter. Characteristic of the large neurones are a highly developed granular endoplasmic reticulum and a large number of axo-somatic synapses. The small neurones have a poorly developed granular endoplasmic reticulum and comparative by few axo-somatic synapses. Injection of horseradish peroxidase (HRP) into the ipsilateral lateral rectus muscle has been used to identify abducens motoneurones which represent 65% of the total number of cells in the abducens nucleus and form part of the large cell population. The remaining unlabelled large neurones (30% of the large cell population) probably represent motoneurones of the retractor bulbi muscles, abducens motoneurones which have failed to transport the HRP, and possibly internuclear neurones. The small neurones (5% of the total cell population) were never labelled by HRP. Axo-somatic and axo-dendritic synapses are numerous. Many of the synaptic terminals form contacts with two or more different postsynaptic elements. Axo-axonic synapses and synapses on the initial segments of large neurones are also present. Nodal synapses and branching of myelinated axons are common findings. Finally, extended areas of close apposition between dendritic membranes are frequently observed.

Abducens Nerve↗
PubMed1977

Ultrastructural observations of the abducens nucleus of the cat after injection of horseradish peroxydase into the lateral rectus muscle.

The ultrastructure of cat abducens motoneurones is described, after labelling by retrograde axonal transport of horseradish peroxydase. The motoneurones were densely covered with synaptic boutons of both the "terminal" and "en passant" types and axo-axonal synapses were observed on the initial segment of motoneurone axons. Within the population of axons forming the VIth nerve, multiple branching was encountered and axons closely apposed at the nodes of Ranvier were seen.

Abducens Nerve↗
PubMed1976

The climbing fibers of the cerebellar cortex, their origin and pathways in cat.

The sources and pathways of the climbing fibers to the cerebellar posterior vermis were studied with comibined electrophysiological and anatomical methods in cats. Recording from identified cerebellar Purkinje cells, monosynaptic climbing fiber (CF) responses have been obtained both for stimulation of the inferior olive (IO) and various parts of the brain stem (BS). CF responses were found to of three types, IO only, BS only or both IO and BS. However the responses to BS stimulation were very few in number in comparison with IO or IO and BS types of responses. The latencies of the responses were shorter for the BS cases consistent with their distance from the cerebellum. A comparison of latencies and the relative responsiveness of the different area of the brain stem which were studied, indicate that part of the CF ascend through the pontine region and enter the cerebellum by way of the medium and superior penduncles. This finding is confirmed by the results of anatomical studies in which degenerating fibers were found in the molecular layer (using the Nauta technique) after lesion of the brachium pontis but not after lesions of the medial portion of the pons. Similarly, injection of radioactive leucine into the pontine nuclei failed to show any labeled fibers in the molecular layer. Horseradish peroxidase (HRP) was injected into localized regions of the posterior vermis after total bilateral destruction of the inferior peduncles. Large numbers of positive, marked cells were still found in the inferior olive. It is concluded that nearly all, if not all, the climbing fibers originate in the inferior olive and that they ascend to the cerebellum by way of all the peduncles.

Afferent Pathways↗