Endings of Peripheral Processes of Spinal Ganglion Cells
We already stated that the principal stem of the spinal ganglion cell. bifurcates into a thin branch directed to the spinal cord, and a thick branch which, joining the corresponding spinal nerve as a sensory fiber, terminates in the skin, mucous membranes, muscles and tendons. In this entire course, from the ganglion to the peripheral termination, sensory fibers can not be distinguished from motor fibers, because both are endowed with myelin sheaths, and exhibit nodes of Ranvier and other structural characteristics of myelinated fibersc.
KeywordsMethylene Blue Muscle Spindle Peripheral Process Gold Chloride Pacinian Corpuscle
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- 1.[In a recent article, Ruffin (1899) recognized our priority in the discovery of the sensory nature of the spindles of Kühne. He also recognized the precise graphic representation of the two distinct terminations in the muscle spindle. As we stated above, Kerschner mentioned these two terminations at the same time as we did , but his descriptions are not precise, and with no illustrations.]Google Scholar
- a.Cajal use of the term intraepidermic is probably a misnomer, since he includes in this category the free endings in the cornea, and the peritrichial endings although they are located in the epithelium and the dermis, respectively. In any event, the long debated issue of whether intraepidermic neural terminations actually exist in the adult skin is apparently resolved in favor of the view that they are represented only by endings in the basal layer of the epidermis, i.e. the deepest stratum of the Malpighian body, and associated in general with Merkel discs, thus forming the Merkel cell-neurite complex. Moreover they are present almost exclusively at mucocutaneous junctions [Darian-Smith (1984) Handbook of Physiology, 3. Am Physiol Soc, Bethesda, pp 739-788 (743-751)].Google Scholar
- b.Mazzoni is misspelled throughout in Textura and Histologie as Manzoni.Google Scholar
- c.It is well recognized today that over 60% of dorsal root fibers are unmyelinated [Langford and Coggeshall (1981) J Comp Neurol 203: 745-750].Google Scholar
- d.Fig. 185.—D, unidentified.Google Scholar
- e.Histologie omits mentioning the equivalent of Fig. 186 in the text.Google Scholar
- f.Fig. 188.—a, biconvex disc; b, neurofibrillar reticle; c, protecting cell.Google Scholar
- g.Fig. 189.—A, stratum basale or germinativum; B, stratum spinosum; C, stratum granulosum; D, stratum corneum; a, dermal-epidermal junction; b, Langerhans cell; e, cell in mitosis.h Textura omits mentioning the equivalent of Fig. 191 in the text. i Fig. 196.—a, equivalent of the sheath of Henle.Google Scholar
- j.This is almost a perfect description of what is known today as the motor innervation of polar regions of the spindle by gamma motor fibers [Matthews (1972) Mammalian muscle receptors and their central actions. Williams and Wilkins, Baltimore, pp 630].Google Scholar
- k.Fig. 199.—a, afferent fiber; c, flattened terminal arborization; d, possibly tunica media; e, borders of endothelial cells.Google Scholar