ISSN:
1432-1106
Keywords:
Abducens nucleus (cat)
;
Peroxidase
;
Neurones
;
Synapses
;
Ultrastructure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Light and electron microscope studies of the abducens nucleus in the cat have disclosed two populations of neurones: large neurones 25 to 75 μm in diameter and small neurones 10 to 25 μm 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00236614
