Summary
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 × 27 μm and a mean volume of 35820 μm3. 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 μm. 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 μm. Primary dendrites had a mean length of 193 μm 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 μm while that of the 5th order processes was 1.5 μm. 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. The surface area and volume of the dendrites constituted 90% and 83% of the total surface area and 46% and 37% of the total volume of the two cells, respectively, excluding the axons. The Ia interneurones differed considerably among themselves with respect to the quantitively investigated parameters. They resembled the inhibitory Renshaw cells of the cat with regard to the number of dendrites, the poverty of spines, and the relationships between cell body diameter and width of primary dendrites.
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References
Berthold C-H, Kellerth J-O, Conradi S (1979) Electron microscopic studies of serially sectioned cat spinal α-motoneurons. I. Effects of microelectrode impalement and intracellular staining with the fluorescent dye “Procion Yellow”. J Comp Neurol 184:709–740
Brown AG, Fyffe REW (1981) Direct observations on the contacts made between Ia afferent fibres and α-motoneurones in the cat's lumbosacral spinal cord. J Physiol (Lond) 313:121–140
Brown AG, Rose PK, Snow PJ (1977) The morphology of spinocervical tract neurones revealed by intracellular injection of horseradish peroxidase. J Physiol (Lond) 270:747–764
Burke RE, Strick PL, Kanda K, Kim CC, Walmsley B (1977) Anatomy of medial gastrocnemius and soleus motor nuclei in cat spinal cord. J Neurophysiol 40:667–680
Cullheim S (1978) Relations between cell body size, axon diameter, and axon conduction velocity of cat sciatic α-motoneurons stained with horseradish peroxidase. Neurosci Lett 8:17–20
Cullheim S, Kellerth J-O (1978) A morphological study of the axons and recurrent axon collaterals of cat sciatic α-motoneurons after intracellular staining with horseradish peroxidase. J Comp Neurol 178:537–558
Cullheim S, Fleshman JW, Gleen LL, Burke RE (1987) Membrane area and dendritic structure of type-identified triceps surae alpha motoneurons. J Comp Neurol 255:68–81
Egger MD, Freeman NCG, Proshansky E (1980) Morphology of spinal motoneurones mediating a cutaneous spinal reflex in the cat. J Physiol (Lond) 306:349–363
Gad P, Jankowska E, McCrea D, Rastad J (1983a) Axon collaterals of spinal interneurones mediating 1a reciprocal inhibition of feline α-motoneurones. Neurosci Lett 14:S127
Gad P, Rastad J, Westman J (1983b) Cell bodies and dendrites of spinal interneurones mediating 1a reciprocal inhibition of feline α-motoneurones. Neurosci Lett Suppl 14:S127
Houchin J, Maxwell DJ, Fyffe REW, Brown AG (1983) Light and electron microscopy of dorsal spinocerebellar tract neurones in the cat: An intracellular horseradish peroxidase study. Q J Exp Physiol 68:719–732
Hultborn H (1972) Convergence on interneurones in the reciprocal Ia inhibitory pathway to motoneurones. Acta Physiol Scand Suppl 375:1–42
Hultborn H, Jankowska E, Lindström S (1971) Recurrent inhibition of interneurones monosynaptically activated from group la afferents. J Physiol (Lond) 215:613–636
Jankowska E, Lindström S (1971) Morphological identification of Renshaw cells. Acta Physiol Scand 81:428–430
Jankowska E, Lindström S (1972) Morphology of interneurones mediating 1a reciprocal inhibition of motoneurones in the spinal cord of the cat. J Physiol (Lond) 226:805–823
Jankowska E, Lundberg A (1981) Interneurones in the spinal cord. TINS 4:230–233
Jankowska E, Roberts WJ (1972a) An electrophysiological demonstration of the axonal projections of single spinal interneurones in the cat. J Physiol (Lond) 222:597–622
Jankowska E, Roberts WJ (1972b) Synaptic actions of single interneurones mediating reciprocal la inhibition of motoneurones. J Physiol (Lond) 222:623–642
Jankowska E, Rastad J, Westman J (1976) Intracellular application of horseradish peroxidase and its light and electron microscopical appearance in spinocervical tract cells. Brain Res 105:557–562
Kernell D, Zwaagstra B (1981) Input conductance, axonal conduction velocity and cell size among hindlimb motoneurones of the cat. Brain Res 204:311–326
Lagerbäck P-Å, Kellerth J-O (1985) Light microscopic observations on cat Renshaw cells after intracellular staining with horseradish peroxidase. II. The cell bodies and dendrites. J Comp Neurol 240:368–376
Lagerbäck P-Å, Ronnevie L-O (1982) An ultrastructural study of serially sectioned Renshaw cells. I. Architecture of the cell body, axon hillock, initial axon segment and proximal dendrites. Brain Res 235:1–15
Malmgren L, Olsson Y (1978) A sensitive method for histochemical demonstration of horseradish peroxidase in neurons following retrograde axonal transport. Brain Res 148:279–294
Rall W (1959) Branching dendritic trees and motoneuron membrane resistivity. Exp Neurol 1:491–527
Rall W (1977) Core conductor theory and cable properties of neurons. In Kandel ER (ed) Handbook of Physiology, section 1, The Nervous System Vol I. Cellular Biology of Neurons, Am Physiol Soc, pp 39–98
Rastad J (1981) Quantitative analysis of axodendritic and axosomatic collateral terminals of two feline spinocervical tract cells. J Neurocytol 10:475–496
Rose PK (1981) Distribution of dendrites from biventer cervicis and complexus motoneurons stained intracellularly with horseradish peroxidase in the adult cat. J Comp Neurol 197:395–409
Rose PK, Richmond FJR (1981) White-matter dendrites in the upper cervical spinal cord of the adult cat: A light and electron microscopic study. J Comp Neurol 199:191–203
Ulfhake B (1984) A morphometric study of the soma, first-order dendrites and proximal axon of cat lumbar α-motoneurones intracellularly labelled with HRP. Exp Brain Res 56:327–334
Ulfhake B, Cullheim S (1981) A quantitative light microscopic study of the dendrites of cat spinal — motoneurons after intracellular staining with horseradish peroxidase. J Comp Neurol 202:585–596
Ulfhake B, Kellerth J-O (1981) A quantitative light microscopic study of the dendrites of cat spinal α-motoneurons after intracellular staining with horseradish peroxidase. J Comp Neurol 202:571–583
Ulfhake B, Kellerth J-O (1983) A quantitative morphological study of HRP-labelled cat α-motoneurones supplying different hindlimb muscles. Brain Res 264:1–19
Ulfhake B, Kellerth J-O (1984) Electrophysiological and morphological measurements in cat gastrocnemius and soleus α-motoneurones. Brain Res 307:167–179
Zwaagstra B, Kernell D (1981) Sizes of soma and stem dendrites in intracellularly labelled α-motoneurones of the cat. Brain Res 204:295–309
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Rastad, J., Gad, P., Jankowska, E. et al. Light microscopical study of dendrites and perikarya of interneurones mediating la reciprocal inhibition of cat lumbar alpha-motoneurones. Anat Embryol 181, 381–388 (1990). https://doi.org/10.1007/BF00186910
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DOI: https://doi.org/10.1007/BF00186910