TY - JOUR
T1 - Strongly Anionic Sites in Peripheral Axons of the Rat Sciatic Nerve
T2 - Light and Electron Microscopic Detection Using Cationic Colloidal Iron
AU - Toda, Kazukiyo
AU - Nishida, Keiichirou
AU - Inoue, Hajime
AU - Ohtsuka, Aiji
AU - Murakami, Takuro
PY - 1995
Y1 - 1995
N2 - Anionic sites in the rat sciatic nerve were studied by light and electron microscopy using a fine-granular cationic colloidal iron staining method (Murakami et al., 1986). The axon, as well as the endoneurium, the epineurium and the basement membrane of Schwann cells, were all confirmed to react strongly to the cationic colloidal iron even at a pH value of 1.0-2.0. Prior hyaluronidase digestion decreased the colloidal stain of the epineurium; chondroitinase ABC weakened that of the endoneurium and the basement membrane of Schwann cells. However, as axons retained stainability with cationic colloidal iron even after combined digestion with hyaluronidase, chondroitinase ABC, heparitinase and keratanase, the authors consider sulfated glycoconjugates and not those substances which are digestible with such common enzymes. The acid groups ionized at pH 1.0 are most likely sulfate groups. Methylation deprived the axon of the reactivity to cationic colloidal iron staining, and even subsequent saponification could not recover this reactivity to its full extent. All these suggested the presence of sulfate groups. In the axon, electron microscopy revealed a deposition of colloidal iron on the external surfaces of microtubules and neurofilaments in the axoplasm and of very fine filaments connecting them. This highly negatively charged intra-axonal network could also serve toward a supportive function in maintaining the spatial distribution of microtubules either mechanically or through electrostatic repulsion or, possibly, serve as an intra-axonal cation exchange reservoir.
AB - Anionic sites in the rat sciatic nerve were studied by light and electron microscopy using a fine-granular cationic colloidal iron staining method (Murakami et al., 1986). The axon, as well as the endoneurium, the epineurium and the basement membrane of Schwann cells, were all confirmed to react strongly to the cationic colloidal iron even at a pH value of 1.0-2.0. Prior hyaluronidase digestion decreased the colloidal stain of the epineurium; chondroitinase ABC weakened that of the endoneurium and the basement membrane of Schwann cells. However, as axons retained stainability with cationic colloidal iron even after combined digestion with hyaluronidase, chondroitinase ABC, heparitinase and keratanase, the authors consider sulfated glycoconjugates and not those substances which are digestible with such common enzymes. The acid groups ionized at pH 1.0 are most likely sulfate groups. Methylation deprived the axon of the reactivity to cationic colloidal iron staining, and even subsequent saponification could not recover this reactivity to its full extent. All these suggested the presence of sulfate groups. In the axon, electron microscopy revealed a deposition of colloidal iron on the external surfaces of microtubules and neurofilaments in the axoplasm and of very fine filaments connecting them. This highly negatively charged intra-axonal network could also serve toward a supportive function in maintaining the spatial distribution of microtubules either mechanically or through electrostatic repulsion or, possibly, serve as an intra-axonal cation exchange reservoir.
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U2 - 10.1679/aohc.58.485
DO - 10.1679/aohc.58.485
M3 - Article
C2 - 8562139
AN - SCOPUS:0028882813
VL - 58
SP - 485
EP - 492
JO - Archives of Histology and Cytology
JF - Archives of Histology and Cytology
SN - 0914-9465
IS - 4
ER -