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The cytoarchitecture in the retinoreceptive zone of the pigeon optic tectum has been studied in Nissl-stained sections taken in four planes. As suggested by a previous study, two cytoarchitectural fields are present. Reconstructed views of the tectum show that the fields are separated by a narrow transition zone approximating to the tectal representation of(More)
The projection of the retina onto the optic tectum of the pigeon has been investigated using silver impregnation methods for degenerating axons and terminals, autoradiographic tracing, and the Golgi methods. Degenerating optic afferents distribute to sublaminae a-d and f of the stratum griseum et fibrosum superficiale over the whole tectum, but two major(More)
Following injection of horseradish peroxidase into the thalamus of one side, the numbers of labelled neurons in the nuclei of the dorsal funiculi and in the trigeminal sensory complex were counted. A comparative study was made of the pattern of labelling after a range of survival times, and animals surviving for 72 h after injection were used to provide(More)
Horseradish peroxidase retrograde transport has been used to locate and make a quantitative study of neurons of the rat spinal cord which project to the thalamus. Across the grey, labelled cells were found in the head and neck of the dorsal horn (in three locations, but not the substantia gelatinosa); in the region of the internal basilar nucleus of Ramón y(More)
The spinal grey projects upon the contralateral superior colliculus via two overlapping pathways in the lateral funiculus. One, more ventrally placed, is the classical spinotectal tract, which crosses immediately in the spinal cord and remains crossed. The other, lying more dorsally, ascends homolaterally but is subject to delayed crossing in the brainstem(More)
Half the monosynaptic spinothalamic neurons in the rat spinal cord lie in the first 4 cervical segments, predominantly in the internal basilar column and ventral horn. The present study shows that both these regions receive primary afferents from the forelimb. The superficial dorsal horn receives few, and the region of the lateral cervical nucleus no(More)
The fine structure of the superficial layer of the optic tectum of the pigeon, Columba livia, has been examined both in normal animals and after unilateral eye removal. Optic afferent terminals distributed throughout sublaminae IIa-f, are principally concentrated at three depths in the retinoreceptive zone. At first, degeneration of optic afferent terminals(More)