[Morphometry of living and metal salt impregnated nerve fibers]

Quantitative comparison on diameter distribution of some structures in vital and fixed neuronal fibres treated with salts of heavy metals has been performed. Rabbit and frog myelin fibres of the ischiadic and vagal nerves impregnated after Bielschowsky--Gross, fixed in 12% neutral formalin and treated after Gomori for acid phosphotase with fixation in cooled acetone have been studied. The diameters of neuronal fibres, axial cylinders and cords have been measured through the microscope with an ocular micrometer. Quantitative comparison of survived and fixed fibres has demonstrated that in the preparations treated with silver and lead salts, as a rule, not the whole fibre is demonstrable, not its axial cylinder, but only a part of the axial cylinder, namely, its centrally situated filamentous cord. It is most probable that, in this case, the axial cord formation is connected with the effect of fixatives. However, axial cord formation is possible in vital, nonfixed fibres in the zone of intersections and swollen incisions. The working hypothesis explaining this phenomenon is represented.