. The development of the sympathetic nervous system in mammals. ws of cells practicallytouching each other end to end may be traced from the mantlelayer, through these breaches, into the proximal parts of the dor-sal nerve-roots (fig. 3, ). Further evidence for themigration of medullary cells into the dorsal nerve-roots is pre-sented by the fact that in many sections where no breaches occur,cells are crowded close to the external limiting membrane in thisregion. In embryos 9 mm., and over in length, this area is always 228 ALBERT KUNTZ zontal line represent the lengths of the embryos
. The development of the sympathetic nervous system in mammals. ws of cells practicallytouching each other end to end may be traced from the mantlelayer, through these breaches, into the proximal parts of the dor-sal nerve-roots (fig. 3, ). Further evidence for themigration of medullary cells into the dorsal nerve-roots is pre-sented by the fact that in many sections where no breaches occur,cells are crowded close to the external limiting membrane in thisregion. In embryos 9 mm., and over in length, this area is always 228 ALBERT KUNTZ zontal line represent the lengths of the embryos in nun.; the figuresin the vertical line indicate the number of cells present in a givenlength of longitudinal sections of the spinal nerves, as they appearin transverse sections of the embryos, taken at random betweenthe point of union of the sensory and the motor roots and theorigin of the communicating rami. Embryos which seemed tobe most normal in their development were selected, and the curveis based on the averages of ten independent counts. This curve. Fig. 7. Diagrammatic transverse section of an embryo 9 or 10 mm. in arrows indicate the course and the direction of the cells migrating from theneural tube and the spinal ganglia into the sympathetic , Aorta, , Path of communicating ramus, , Dorsal nerve-root, ,Anlagen of prevertebral plexuses, , Spinal ganglion, , Spinal , Suprarenal bodies, sy., Sympathetic trunks, , Ventral , Wolffian body. indicates that the rate of migration reaches its maximum in em-bryos 9 mm. in length, and that migration practically ceaseswhen a length of 13 mm. is attained. It also indicates that arelatively small but fairly constant number of cells remains inthe spinal nerves after migration has ceased. As already indicated in reviewing the literature, Kohn and Neu-mayer have attempted to account for the cells giving rise to thesympathetic nervous system, by local di
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmammals, bookyear1910
