Summary
Conventional cobalt chloride procedures, using either diffusion into cut nerves or application via an electrode, can only incompletely resolve nerve cells for light microscopical observation. Enhanced resolution can be obtained by the addition of small quantities of serum albumin to the cobalt chloride. This allows sufficient contrast many nerve cells and enhances the details of thin fibres and their appendages. That this should be possible is of cardinal importance for combined electrophysiological and structural studies.
The present account also illustrates that in Dipterous insects there are certain conditions where cobalt chloride will move from one neuron into another. This movement is between functionally contiguous neurons and is here described from the visual system, with reference to electrophysiological studies that employ procion yellow identifications. Transynaptically filled neurons are only faintly resoluble in whole mounts. A block modification of the Timm's enhancement procedure is described which will reveal the finest details of neurons in thick sections and will also reveal nerve cells that have taken up minute quantities of CoCl2 after passage across at least two synapses. These observations are discussed with reference to their implications and applications for electrophysiological mappings of structural pathways.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bennet, M.V.L.: Permeability and structure of electrotonic junctions and intracellular movements of tracers. In: Intracellular staining in neurobiology (S.B. Kater and C. Nicholson, eds.), pp. 115–134. Berlin-Heidelberg-New York: Springer 1973
Dvorak, D.R. Bishop, L.G., Eckert, H.E.: On the identification of movement detectors in the fly optic lobe. J. comp. Physiol.100, 5–23 (1975)
Gray, E.G.: Presynaptic microtubules and their association with synaptic vesicles. Proc. roy. Soc. B190, 369–372 (1975)
Goodman, C.: Anatomy of Locust interneurons: constancy and variability. J. comp. Physiol.95, 185–201 (1974)
Hausen, K.: Functional characterization and anatomical identification of motion sensitive neurons in the lobula plate of the blow flyCalliphora erythrocephala. Z. f. Naturforsch., in press (1976)
Honegger, H.-W., Schürmann, F.W.: Cobalt sulphide staining of optic fibres in the brain of the cricket,Gryllus campestris. Cell Tiss. Res.159, 213–225 (1975)
Karnovsky, M.J.: A formaldehyde-glutaraldehyde fixation of high osmolarity for use in electronmicroscopy. J. Cell Biol.27, 137A (1965)
O'Shea, M.L, Rowell, C.H.F., Williams J.L.D.: The anatomy of a locust visual interneurone; the descending contralateral movement detector. J. exp. Biol.60, 1–12 (1974)
Payton, B.W., Bennet, M.V.L., Pappas, G.D.: Permeability and structures of junctional membranes at an electrotonic synapse. Science166, 1641–1643 (1969)
Pitman, R.M., Tweedle, C.D., Cohen, M.J.: Branching of central neurons: intracellular cobalt injections for light and electron microscopy. Science176, 412–414 (1972)
Pitman, R.M., Tweedle, C.D., Cohen, M.J.: The dendritic geometry of an insect common inhibitory neuron. Brain Res.60, 465–470 (1973)
Politoff, A., Pappas, G.D., Bennet, M.V.L.: Cobalt ions cross an electrotonic synapse if cytoplasmic concentration is low. Brain Res.76, 343–346 (1974)
Ramon-Moliner, E.: A source of error in the study of Golgi-stained material. Arch. ital. Biol.105, 139–148 (1967)
Strausfeld, N.J.: Atlas of an insect brain. Berlin-Heidelberg-New York: Springer 1976
Székely, G.: The morphology of motorneurons and dorsal root fibres in the frog spinal cord. Brain Res.103, 275–290 (1976)
Tyrer, N.M., Altman, J.S.: Motor and sensory flight neurons in a locust demonstrated using cobalt chloride. J. comp. Neurol.157, 117–138 (1974)
Tyrer, N.M., Bell, E.M.: The intensification of cobalt filled neuron profiles using a modification of Timm's sulphide-silver method. Brain Res.73, 151–155 (1974)
Zawarzin, A.: Zur Morphologie der Nervenzentren. Das Bauchmark der Insekten. Ein Beitrag zur vergleichenden Histologie. Z. wiss. Zool.122 323–424 (1924)
Author information
Authors and Affiliations
Additional information
We thank Drs C.H.F. Rowell, J. Altman, K. Hausen and L. Williams for comments and critical readings of early and final drafts of the manuscript, and to Mrs. G. Pouvatchy for typing.
Rights and permissions
About this article
Cite this article
Strausfeld, N.J., Obermayer, M. Resolution of intraneuronal and transynaptic migration of cobalt in the insect visual and central nervous systems. J. Comp. Physiol. 110, 1–12 (1976). https://doi.org/10.1007/BF00656777
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00656777