A manual of diseases of the nervous system . seem to become changed in chemical composition, sincethey are stained less deeply by osmic acid. Ranvier suggests thattheir fatty matter may undeigo a process of saponification. Ultimatelythey seem to pass through the sheath, are taken up by connective-tissue cells and lymphatic cells in the vicinity (as in J), and aregradually, for the most part, removed. By the time the myelin is insmall globules the nuclei cease to multiply. On the removal of theproducts of degeneration the sheath shrinks, and looks empty inplaces, but here and there it is enlarg
A manual of diseases of the nervous system . seem to become changed in chemical composition, sincethey are stained less deeply by osmic acid. Ranvier suggests thattheir fatty matter may undeigo a process of saponification. Ultimatelythey seem to pass through the sheath, are taken up by connective-tissue cells and lymphatic cells in the vicinity (as in J), and aregradually, for the most part, removed. By the time the myelin is insmall globules the nuclei cease to multiply. On the removal of theproducts of degeneration the sheath shrinks, and looks empty inplaces, but here and there it is enlarged by the nuclei, protoplasm,and a few remaining myelin globules (H). Hence in transversesection many small sheaths are seen with a few of larger size wherethey have been cut across at these swellings. In the rabbit the first changes are visible at the end of twenty-fourVOL. I. 4 50 LESIONS OF NERVES. hours; tbe first complete interruption of the myelin and axis-cylincleroccurs about the end of the second day ; the process of destruction is. Fig. 34. A B Fig. 33.—A-J, Degeneration of nerve-fibres (osmic acid and carminestaining). A, from sciatic of rabbit four days after section; B, C, same,fifty hours after section; D, a fibre stained with carmine only, to showthe axis-cylinder ; P, G, fibres from pigeon three days after section ; H, two• fibres from pneumogastric of rabbit six days after section ; J, a Ivmphaticcell from interfibrillar connective tissue, containing globules of myelinthat it has taken up. In all the figures n, n, nuclei; x, x, constrictions ofthe myelin produced by the growth of the protoplasm; ac, axis-cylinder. K, L, Regeneration of nerve-fibres. K, from pneumogastric of rabbitseventy-two days after section ; L, from sciatic of rabbit ninety days aftersection; e, rounded end of white substance of central end of nerve; *,sheatl); na, new axis-cylinder. In L are two globules of myelin remainingfrom the degeneration of the old fibre. Fig. 34.—Degenerating
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnervoussystem, bookye
