Light and electron microscopy studies of the ulnar, saphenous, and caudal cutaneous sural nerves of the dog

Abstract

Transverse sections of the ulnar, saphenous, and sural nerves taken at specific levels in normal, young-adult beagle dogs were examined qualitatively and quantitatively at both the light and electron microscopic levels. The aim of this investigation was to provide baseline information for future studies of peripheral nerve disease in this species. A systematic sampling technique was used for the determination of nerve components (i.e., unmyelinated axons and Schwann cell and fibroblast nuclei). In all nerves sampled, the average size distribution for unmyelinated axons was unimodal, and most of the axons were 0.4-1.1 micron in diameter. Within this range, there were slight individual and nerve-to-nerve variations in the location of the largest diameter peak. The mean densities of Schwann cell nuclei (numbers/mm2) ranged from 841/mm2 in the palmar branch of the ulnar nerve, to 1,223/mm2 in the caudal cutaneous sural nerve, being nearly four times the average density or fibroblast nuclei. In every animal and in almost every nerve, a few abnormalities were found; and these should be kept in mind when assessing peripheral nerves in the dog.

Axon and muscle spindle hyperplasia in the myostatin null mouse

“…Resin sections were left to dry on a hot surface (60 °C) overnight. Subsequently, sections were covered with 1% toluidine blue with 1% sodium borate for 1 min, washed in distilled water, dried and mounted using DPX, as previously performed (Illanes et al., 1990).…”

Specific paucity of unmyelinated C‐fibers in cutaneous peripheral nerves of the African naked‐mole rat: Comparative analysis using six species of bathyergidae

“…Solid symbols correspond to A-fibers and open symbols to C-fibers. For species not examined in this study, data were taken from: mouse (Milenkovic et al,2007; Wetzel et al,2007; Park et al,2008), rat (Scadding,1980; Lynn,1984; Carter and Lisney,1987), cat (Sherrington,1894; Gasser and Grundfest,1939; Douglass et al,1934), and dog (Illanes et al,1990). Scale bars = 2 μm in A–F; 0.5 μm in A′–F′.…”

“…The ability to detect noxious stimuli is fundamental for an organism's survival and has presumably been the selection pressure behind the evolution of an elaborate repertoire of nociceptors in mammals to carry out this task (Kavaliers,1988; Walters,1996; Smith and Lewin,2009). C-fiber nociceptors usually outnumber A-fibers (predominantly non-nociceptors) in nerves innervating the skin, including the saphenous nerve (Scadding,1980; Alpsan and Lal,1980; Lynn,1984; Jancso et al,1985; Carter and Lisney,1987; Illanes et al,1990; Milenkovic et al,2007; Wetzel et al,2007; Park et al,2008) and sural nerve (Ochoa and Mair,1969; Schwab et al,1984; Jenq and Coggeshall,1984a, b, 1985a, b; Peyronnard et al,1986). We have previously shown that, in comparison with other rodents, the naked mole-rat saphenous nerve has a C-fiber deficit, resulting in a very low C:A-fiber ratio (Park et al,2008), which is confirmed in this study (Fig.…”

“…In the present study, the range in the mean C-fiber axon diameter from sural, common peroneal, and tibial nerves was from 0.06 μm in the Damaraland mole-rat to 0.12 μm in the silvery mole-rat (Tables 1, 2). When it has been investigated in other rodent species, the C-fiber axon diameter distribution has been observed to be unimodal in saphenous (Scadding,1980; Alpsan and Lal,1980; Lynn,1984; Illanes et al,1990), sural (Ochoa and Mair,1969; Schwab et al,1984; Schmalbruch,1986; Hoffmeister et al,1991), and common peroneal and tibial nerves (Schmalbruch,1986). We could confirm in every nerve, from all species examined, that there was a unimodal distribution for C-fiber diameter.…”

“…The saphenous nerve is frequently used in an in vitro skin nerve preparation to characterize sensory afferent fiber properties (Reeh,1986; Koltzenburg and Lewin,1997; Koltzenburg et al,1997; Milenkovic et al,2007, 2008; Wetzel et al,2007; Lechner and Lewin,2009). Measurements of the C:A-fiber ratio in the saphenous nerve by transmission electron microscopy have shown that C-fibers outnumber A-fibers with a ratio of ∼4:1 in a number of mammalian species: rat ( Rattus norvegicus ; Scadding,1980; Alpsan and Lal,1980; Lynn,1984; Jancso et al,1985; Carter and Lisney,1987), mouse ( Mus musculus ; Stucky et al,2002; Wetzel et al,2007; Milenkovic et al,2007; Stürzebecher et al,2010), and dog ( Canis lupus familiaris ; Illanes et al,1990). The sural nerve, which also contains predominantly cutaneous axons and innervates the lateral calf and foot (Peyronnard and Charron,1982; Lewin and McMahon,1991a, b), has also been observed to contain a C:A-fiber ratio of ∼4:1 in both humans and rabbits, Oryctolagus cuniculus (Ochoa and Mair,1969; Schwab et al,1984).…”