Quantitative analysis of axodendritic and axosomatic collateral terminals of two feline spinocervical tract cells

Rastad, Jonas

doi:10.1007/bf01262417

Cited by 9 publications

(2 citation statements)

References 45 publications

(55 reference statements)

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“…SCT and PSDC neurons give off collateral branches ventral to the cell soma, and thus may also function as interneurons Brown and Fyffe, 1981). SCT collaterals are reported to contact cell bodies and large dendrites (Rastad, 1981a;Maxwell and Koerber, 19861, a quite different distribution than the one described in the present study. This difference may arise from the different species used in the studies, but it may also reflect a fundamental dichotomy between the influences of local axon interneurons and projection cells on segmental sensory integration.…”

Section: Local Synaptic Circuits In Lamina Iii/ivcontrasting

confidence: 63%

Synaptic connectivity of local circuit neurons in laminae III and IV of hamster spinal cord

Schneider

Sandiford

Kavookjian

et al. 1995

J of Comparative Neurology

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The present study was undertaken to examine the morphological bases of local synaptic interactions between dorsal horn interneurons. Seven interneurons responding to innocuous mechanical stimuli were intracellularly recorded in lamina III/IV of an isolated preparation of hamster spinal cord with partially intact innervation from an excised patch of hairy skin. Axonal arborizations were stained with horseradish peroxidase (HRP) and examined with an electron microscope. Five cells had extensive synaptic terminations (375-1,785 boutons/axon) with localized distributions (rostrocaudal distance, 425-1,251 microns) overlapping the dendritic trees. Two cells gave rise to deep stem axons that bifurcated into rostrocaudal daughter branches with collaterals ventral to the parent cell bodies (79-661 boutons/axon). Axons of local interneurons were thinly myelinated and formed terminal and en passant enlargements (mean [+/- S.D.] diameter = 0.88 +/- 0.24 microns, n = 157) containing clear, round vesicles 20-60 nm in diameter. Collateral branches of deep axon cells produced round, vesicle-containing boutons comparable in diameter (0.93 +/- 0.22 microns, n = 31) to local axon cells. Both types of interneurons formed asymmetric synaptic contacts with dendritic profiles, but not with cell bodies or axon terminals. Postsynaptic profiles contained sparse ribosomes and had a mean diameter of 1.0 +/- 0.5 microns (n = 49), significantly smaller than a population of identified proximal dendrites (2.3 +/- 0.9 microns, n = 47). HRP-labeled boutons were rarely (5/45 or 11%) in synaptic contact with more than one profile. We conclude that lamina III/IV interneurons make axodendritic synapses predominantly with distal dendrites. Thus, terminations of deep dorsal horn interneurons appear to have a postsynaptic distribution overlapping with axodendritic contacts formed by several functional classes of cutaneous sensory fibers signaling innocuous mechanical stimuli. Such overlap suggests that local spinal networks selectively and strongly influence afferent signals at initial stages of somatosensory integration.

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Section: Local Synaptic Circuits In Lamina Iii/ivcontrasting

confidence: 63%

Synaptic connectivity of local circuit neurons in laminae III and IV of hamster spinal cord

Schneider

Sandiford

Kavookjian

et al. 1995

J of Comparative Neurology

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“…1977;Berthold et al 1979;Brown and Fyffe 1981). Since intracellularly injected horseradish peroxidase (HRP) provides much better means for extensive analysis of especially the distal parts of cellular processes (Jankowska et al 1976;Rastad 1981 ;Ulfhake and Kellerth 1981 ;Houchin et al 1983), we have used this stain to re-examine the morphology of Ia interneurones selecting those with input from knee extensors quadricepts, which have been found to constitute a highly functionally homogeneous subpopulation (Jankowska and Roberts 1972a, b;Hultborn 1972). The present reports presents the data on the light microscopic appearance of perikarya and dendrites of these neurones with attention to differences between the cells belonging to the same functional population.…”

Section: Introductionmentioning

confidence: 99%

Light microscopical study of dendrites and perikarya of interneurones mediating la reciprocal inhibition of cat lumbar alpha-motoneurones

et al. 1990

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Interneurones which mediate disynaptic inhibition from la muscle spindle afferents of the quadriceps nerve to lumbar alpha-motoneurones were stained with intracellular injection of horseradish peroxidase. Seven best stained and most satisfactorily preserved cells were selected for analysis, and the light microscopic morphology of their cell bodies and dendrites were quantitatively investigated in parasagittal sections. The perikarya were located dorsal or dorso-medial to the motoneurones; they had mean diameters of 51 x 27 microns and a mean volume of 35,820 microns 3. The cells had 3 to 7 dendrites, which were arranged asymmetrically around the parent somata. The dendrites extended mainly in the dorso-ventral direction, in which the mean tip to tip distance for each cell was 1742 microns. The dendrites had few spines and they branched almost only in bifurcations. On the average, each process divided 3.5 times and in each cell they gave rise to 14.9 branching points as well as a total combined length of more than 7000 microns. Primary dendrites had a mean length of 193 microns which was generally shorter than the lengths of the branches of higher order. A more detailed analysis of two cells revealed the mean width of primary dendrites to be 5.6 microns while that of the 5th order processes was 1.5 microns. The mean tapering of individual dendritic branches per unit length was 17%, being somewhat more pronounced for the distally located segments, while at branching points the sum of daughter processes approximately equalled the diameter of the parent process.(ABSTRACT TRUNCATED AT 250 WORDS)

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Morphometric synaptology of a whole neuron profile using a semiautomatic interactive computer system

Saito

Niki

1983

Cytometry

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We propose a new method of dealing with morphometric synaptology that processes all synapses and boutons around the HRP marked neuron on a large composite electron micrograph, rather than a qualitative or a piecemeal quantitative study of a particular synapse and/or bouton that is not positioned on the surface of the neuron. This approach requires the development of both neuroanatomical procedures, by which a specific whole neuronal profile is identified, and valuable specialized tools, which support the collection and analysis of a great volume of morphometric data from composite electron micrographs, in order to reduce the burden of the morphologist.The present report is also concerned withThe importance of quantitative electron microscopic study of neurons and their synapses has gained increasing recognition. This type of neuroanatomy, however, presents great difficulty and involves much time-consuming work. As yet, reliable methods for such studies have not been fully developed (9,16). This paper proposes a new method of dealing with quantitative synaptology that treats all recorded synapses and boutons around a whole neuron profile marked with horseradish peroxidase (HRP), rather than a qualitative or a piecemeal quantitative study of a particular synapse andlor bouton that is not positioned on the surface of the neuron. This approach requires the development of two procedures to achieve a reliable study.Address reprint requests to Dr. Kiichiro Saito, Department of Anatomy, Institute of Basic Medical Sciences, The University of Tsukuba, Sakura-mura, Niihari-gun, Ibaraki 305, Japan. the total and reliable semi-automatic interactive computer system for gathering and analyzing morphometric data that has been under development in our laboratory. A morphologist performs the pattern recognition portion by using a large-sized tablet digitizer and a menu-sheet command, and the system registers the various morphometric values of many different neurons and performs statistical analysis.Some examples of morphometric measurements and analysis show the usefulness and efficiency of the proposed system and method.Key terms: Morphometry, computer system, neuron and synapses, electron micrographsThe first is the neuroanatomical method, which refers to preparation processes such as the HRP marking technique, by which a specific neuron is identified, and the composite photographic technique in which the size of the field selected for study depends on the magnification of the electron micrographs. The second procedure is the development of valuable specialized tools, that is, a semiautomatic interactive computer system that uses a large graphic tablet digitizer, which drastically reduces the burden of the morphologist and facilitates data collection and analysis of a whole neuron profile. MATERIALS AND METHODSExperimental Materials Adult cats (2.4-5.1 kg) were used for the present study. Under Nembutal (30 mg/kg; ip) anesthesia, multiple stereotaxic injections of 20% HRP in 0.05 M Tris HC1 buffer were made into a wide area of ...

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Quantitative analysis of axodendritic and axosomatic collateral terminals of two feline spinocervical tract cells

Cited by 9 publications

References 45 publications

Synaptic connectivity of local circuit neurons in laminae III and IV of hamster spinal cord

Synaptic connectivity of local circuit neurons in laminae III and IV of hamster spinal cord

Light microscopical study of dendrites and perikarya of interneurones mediating la reciprocal inhibition of cat lumbar alpha-motoneurones

Morphometric synaptology of a whole neuron profile using a semiautomatic interactive computer system

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