The projection to the mesencephalon from the sensory trigeminal nuclei. An anatomical study in the cat.

The terminal areas and the cells of origin of the projection from the sensory trigeminal nuclei to the mesencephalon were investigated, using the method of anterograde and retrograde transport of horseradish peroxidase or wheat germ agglutinin-horseradish peroxidase conjugate. Injection of tracer into the nucleus interpolaris or nucleus oralis (in the latter cases with involvement of the nucleus principalis) resulted in dense anterograde labeling in the deep and intermediate gray layers of the contralateral superior colliculus, extending throughout the rostrocaudal extent of the colliculus with the exception of its caudalmost part, which was not labeled. Minor projections to the intercollicular nucleus, posterior pretectal nucleus and nucleus of Darkschewitsch were found.

Synaptic terminals in the ventroposterolateral nucleus of the thalamus from neurons in the dorsal column and lateral cervical nuclei: an electron microscopic study in the cat.

The afferent fibres to the ventroposterolateral nucleus (VPL) of the contralateral thalamus from neurons in the dorsal column nuclei (DCN) and the lateral cervical nucleus (LCN) were labelled by anterograde transport of wheat germ agglutinin-horseradish peroxidase conjugate and subsequent histochemical processing with tetramethyl benzidine. In accordance with the results of previous light microscopical studies using the degeneration method or autoradiographic tracing technique, the distribution of the afferents from the DCN and LCN in the VPL differed considerably. Thus the DCN terminals, which were calculated to constitute about 7-8% of the total number of boutons in the VPL, were found throughout the entire VPL, whereas the LCN terminals were mainly located in its dorsal and dorsolateral parts, where they made up about 1% of the total number of boutons.

Somatotopic termination of spinal afferents to the feline lateral cervical nucleus.

The labelling pattern of the feline lateral cervical nucleus (LCN) was investigated after pressure injections of lectin-conjugated horseradish peroxidase into cervical, thoracic or lumbar segments of the spinal cord. Sixteen cats received a 5-8 nl injection staining large parts of mainly the ipsilateral grey matter of a single segment. Light microscopic examination of frozen sections reacted with tetramethylbenzidine showed a somatotopic organization in the LCN.

The projection to the mesencephalon from the dorsal column nuclei. An anatomical study in the cat.

The terminal areas and cells of origin of the projection from the dorsal column nuclei to the mesencephalon were investigated by the intra-axonal transport method. Following injection of wheat germ agglutinin-horseradish peroxidase conjugate into the dorsal column nuclei, anterograde labeling was observed in several regions of the midbrain. The main terminal area was situated at the level of transition between the superior and inferior colliculus on the side contralateral to the injection site and comprised the intercollicular nucleus and part of the external and pericentral nuclei of the inferior colliculus and of the nucleus of the brachium of the inferior colliculus, but there were also projections to the caudal half of the deep and intermediate gray layers of the superior colliculus, the anterior and posterior pretectal nuclei, the nucleus of Darkschewitsch and nucleus ruber.

The spinomesencephalic tract in the cat: its cells of origin and termination pattern as demonstrated by the intraaxonal transport method.

The cells of origin and terminal areas of the feline spinomesencephalic tract were investigated by the intraaxonal transport method. Following injection of wheat germ agglutinin-horseradish peroxidase conjugate into the cervical and lumbar enlargements, anterograde labelling was observed in several regions of the dorsal midbrain. The main terminal areas were the periaqueductal gray matter, the intercollicular nucleus, the posterior pretectal nucleus and the nucleus of Darkschewitsch.

The termination in the mesencephalon of fibres from the lateral cervical nucleus. An anatomical study in the cat.

The termination in the dorsal mesencephalon of fibres from the lateral cervical nucleus (LCN), recently discovered with the retrograde tracing technique, was investigated by both the degeneration method and anterograde transport of lectin-conjugated horseradish peroxidase. Both strategies gave similar results. The termination area was found to be situated at the level of transition between the superior and inferior colliculi and comprises mainly the intercollicular nucleus and the deep and intermediate layers of the posterolateral pole of the superior colliculus.