The Morphology of Spinal Afferent-Efferent Relationships in Vertebrates

Joseph, Barry S.; Whitlock, David G.

doi:10.1159/000125490

Cited by 26 publications

(9 citation statements)

References 17 publications

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“…In T. hermanni and in P. reliculatus, however, almost no fibers were found to extend into the ventral horn. Similar observations have been made in the turtle Pseudemys scripta elegans and Caiman sclerops [Joseph and Whitlock, 1968a]. The present results in the lizard T. nigropunctatus are consistent with data in other lizards presented by Joseph and Whitlock [1968a], These authors studied the lumbar dorsal root distribution in various terrestrial vertebrates.…”

Section: Discussionsupporting

confidence: 92%

“…Similar observations have been made in the turtle Pseudemys scripta elegans and Caiman sclerops [Joseph and Whitlock, 1968a]. The present results in the lizard T. nigropunctatus are consistent with data in other lizards presented by Joseph and Whitlock [1968a], These authors studied the lumbar dorsal root distribution in various terrestrial vertebrates. In the lizards Ctenosaura hemilopha and Iguana iguana, pri mary afferent fibers could be traced along the lateral margin of the ven tral horn and in several instances appeared to cascade down along the dorsal dendrites to a point very close to the somata of the motoneurons from which these dendrites originate.…”

Section: Discussionsupporting

confidence: 92%

“…Accompanying this adaptive increase, Joseph and Whitlock [1968a] claim a closer potential coupling between the primary input and output systems of the spinal cord in lizards than in the caiman. The present results in T. hermanni and T. nigropunctatus are in keeping with the hypothesis of Joseph and Whitlock [1968a]. Moreover, the pres ent data suggest that the latter hypothesis not only applies to the hindlimb, but to the forelimb as well.…”

Section: Discussionmentioning

confidence: 97%

“…The considerable variation in lumbar dorsal root distribution has been correlated by Joseph and Whitlock [1968a] with the gross hindlimb structure of the reptiles studied: the caiman limb has no appreciable ca pacity for fine prehensile movements, whereas the lizards mentioned above possess long multijointed digits which give their limbs a marked prehensile character. Accompanying this adaptive increase, Joseph and Whitlock [1968a] claim a closer potential coupling between the primary input and output systems of the spinal cord in lizards than in the caiman.…”

Section: Discussionmentioning

confidence: 97%

“…Experimental studies in the above-mentioned reptiles have indicat ed that the organization of descending pathways to the spinal cord [ten Donkelaar, 1976a, b] and propriospinal connections Kusuma and ten Donkelaar, in preparation] is definitely related to their type of locomotion. Joseph and Whitlock [1968a] have shown that the segmental distribution of lumbar dorsal roots in several reptilian spe cies is clearly related to the limb structure and function present in each reptilian form studied. A few other reports providing experimental data on dorsal root projections are available for reptiles [Goldby and Robin son, 1962; yon der Sloot, 1968], In the present study the spinal gray has been divided into a number of areas according to Kusuma el al.…”

Section: Introductionmentioning

confidence: 97%

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Dorsal Root Projections in Various Types of Reptiles

Kusuma¹,

Donkelaar²

1980

Brain Behav Evol

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The distribution of dorsal root fibers into the spinal cord as well as to the brainstem have been studied in various types of reptiles. At the site of entrance into the spinal cord no clear segregation of large fibers medially and smaller fibers laterally has been observed. A peculiarity for reptiles seems to be a lateral bundle of primary afferent fibers which traverses the dorsal part of the lateral funiculus. The fibers of this bundle enter the spinal gray at the lateral side of the dorsal horn. Notable variation in the distribution of dorsal root fibers has been observed in the reptiles studied. In the turtle Testudo hermanni and in the snake Python reticulatus almost no fibers were found to extend into the ventral horn. However, in the lizard Tupinambis nigropunctatus a distinct projection into the ventral horn was observed. This closer potential coupling between the primary input and output systems of the spinal cord than in the turtle Testudo hermanni seems to be related to the long multijointed digits in the lizard studied which give its limbs a marked prehensile character.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

See 3 more Smart Citations

Dorsal Root Projections in Various Types of Reptiles

Kusuma¹,

Donkelaar²

1980

Brain Behav Evol

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Thalamotelencephalic projections in the turtle (Pseudemys scripta)

Hall

Ebner

1970

J of Comparative Neurology

239

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The telencephalic projections of the turtle thalamus were studied using the Fink-Heimer ('67) technique for staining dezenerated axons and their terminals.Large thalamic lesions produced terminal degeneration i n the basal telencephalic nuclei, the core of the dorsal ventricular ridge and the outer half of layer I i n general cortex. A variety of control lesions confirmed that these projections arisc i n the thalamus. Circumscribed thalamic lesions revealed first, that there is some degree of spatial organization in the turtlc's thalamocortical projection system and second, that at least one sensory relay nucleus, the dorsal lateral geniculate, projects to general cortex. Detailed comparisons of the turtle's thalamotelencephalic projections with thosc present i n two primitive mammalian species, the hedgehog and the opossum, provided a basis for identifying probablc homologies in thc forebrains of reptilcs and mnmmals.

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An anatomical study of some somesthetic afferents to the intercollicular terminal zone of the midbrain of the opossum

RoBards

Watkins

Masterton

1976

J of Comparative Neurology

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Following lesions of the dorsal column nuclei, spinal cord and sensorimotor cortex, anterograde degeneration was traced to a common target in the central midbrain; the intercollicular terminal zone. Although not all the midbrain projections of the three pathways are contained within this zone, it receives overlapping projections from each of the three body-related somesthetic pathways studied. The intercollicular terminal zone covers the entirety of the external nucleus of the inferior colliculus and the intercollicular nucleus of Mehler, spilling over into adjacent parts of the central gray and deep layers of the superior colliculus. Little evidence of somatotopy in the somesthetic projections was disclosed, and bilateral input was found in each experimental case, regardless of the type of lesion. Golgi-stained material was examined to explore the basis of the extensiveness of the terminal zone. These materials showed that the dendritic spread of neurons in the external nucleus of the inferior colliculus and the intercollicular nucleus, taken together, covers the entirety of the intercollicular terminal zone. That is, the dendrites invade the same portions of the central gray and deep layers of the superior colliculus which are covered by the terminal field. We conclude that a tripartite division of the sensory midbrain may be justified: with the somesthetic modality being represented anatomically in a fashion at least roughly analogous to that of vision and audition.

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The Morphology of Spinal Afferent-Efferent Relationships in Vertebrates

Cited by 26 publications

References 17 publications

Dorsal Root Projections in Various Types of Reptiles

Dorsal Root Projections in Various Types of Reptiles

Thalamotelencephalic projections in the turtle (Pseudemys scripta)

An anatomical study of some somesthetic afferents to the intercollicular terminal zone of the midbrain of the opossum

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