Perioculomotor cell groups in monkey and man defined by their histochemical and functional properties: reappraisal of the Edinger-Westphal nucleus.

The perioculomotor region contains several functional cell groups, including parasympathetic preganglionic neurons of the ciliary ganglion, motoneurons of multiply innervated muscle fibers (MIF) of extraocular muscles, and urocortin-positive neurons. In this study, midbrain sections of monkey and human were treated with antibodies against choline acetyltransferase (ChAT), cytochrome oxidase (CytOx), nonphosphorylated neurofilaments (NP-NF), chondroitin sulfate proteoglycan (CSPG), and urocortin (UCN) to identify them by their histochemical properties. To facilitate the comparison between species, a new nomenclature was introduced (see also May et al.

Histochemical differences between motoneurons supplying multiply and singly innervated extraocular muscle fibers.

The extraocular muscle fibers of vertebrates can be classified into two categories: singly innervated fibers (SIFs) and multiply innervated fibers (MIFs). In monkeys, the motoneurons of SIFs lie within the oculomotor, trochlear, and abducens nucleus, whereas the motoneurons of MIFs appear in separate subgroups in the periphery of the classical nuclei borders. In the present study, we investigated the histochemical properties of SIF and MIF motoneurons by using combined tract-tracing and immunofluorescence techniques.

Proprioception and palisade endings in extraocular eye muscles.

Palisade endings occur only in extraocular muscles, and their function is unknown. They form a cuff of nerve terminals around the tips of muscle fibers. We describe here the advantages of using antibodies to a synaptosomal-associated protein (SNAP-25) to study properties of palisade endings in man, monkey, and rat.

Palisade endings in extraocular eye muscles revealed by SNAP-25 immunoreactivity.

Palisade endings form a cuff of nerve terminals around the tip of muscle fibres. They are found only in extraocular muscles, but no definite evidence for their role in eye movements has been established. Palisade endings have been reported in all species so far investigated except the rat.