Summary
The morphological characteristics of dendrites in layers of the cerebral cortex above laminar lesions induced by ionizing particle irradiation have been studied in the striate field of rat at various survival times. Within two weeks following irradiation an increasing number of dendrites display unusual alterations inferred to be signs of degeneration.
Degenerating dendrites can be characterized by a dense cytoplasmic matrix, disruption of mitochondria, presence of dense bodies, irregular outline and a marked alteration of the plasmalemma in its dimensions and staining properties. Some degenerating dendrites possess a large accumulation of dense subsynaptic material and are contacted by synapses with enlarged and altered synaptic clefts. A few dendrites contain extensive membranous whorls. Engulfment by reactive astrocyte processes is a common feature and often includes the presynaptic axonal knob, but only the degenerating dendrite has been observed within glial cytoplasm. The inference that the majority of degenerating dendrites in this material are apical dendrites of pyramidal cells suggests that either shaft synapses are common for these cells, protuberances may retract during degeneration, or spines are lost due to loss of afferent terminals.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Brusted, T., P. Ariotti and J. Lyman: Experimental setup and dosimetry for investigating biological effects of densely ionizing radiations. Univ. of Cal. Rad. Reports 9454, 30 pp. (1960).
Colonnier, M.: Experimental degeneration in the cerebral cortex. J. Anat. (Lond.) 98, 47–53 (1964).
—: Synaptic patterns on different cell types in the different laminae of the cat visual cortex: An electron microscope study. Exp. Brain Res. 9, 268–287 (1968).
Grant, G.: Degenerative changes in dendrites following axonal transection. Experientia (Basel) 21, 722 (1965).
—: Silver impregnation of degenerating dendrites, cells and axons central to axonal transection. II. A Nauta study on spinal motor neurons in kittens. Exp. Brain Res. 6, 284–293 (1968).
Grant, G., and H. Aldskogius: Silver impregnation of degenerating dendrites, cells and axons central to axonal transection. I. A Nauta study on the hypoglossal nerve in kittens. Exp. Brain Res. 3, 150–162 (1967).
—, and J. Westman: Degenerative changes in dendrites central to axonal transection. Electron microscopical observations. Experientia (Basel) 24, 169–170 (1968).
—: The lateral cervical nucleus in the cat. IV. A light and electron microscopical study after midbrain lesions with demonstration of indirect Wallerian degeneration at the ultrastructural level. Exp. Brain Res. 7, 51 (1969).
Kruger, L., and L.I. Malis: Distribution of afferent and efferent fibers in the cerebral cortex of the rabbit revealed by laminar lesions produced by heavy ionizing particles. Exp. Neurol. 10, 509–524 (1964).
—, and D.S. Maxwell: Wallerian degeneration in the optic nerve of a reptile: An electron microscopic study. Amer. J. Anat. 125, 247–270 (1969).
Luse, S.A., and R.E. McCaman: Electron microscopy and biochemistry of Wallerian degeneration in the optic and tibial nerves. Amer. J. Path. 33, 586 (1957).
Majorossy, K., and M. Rethelyi: Synaptic architecture in the medial geniculate body. Exp. Brain Res. 6, 306–323 (1968).
Malis, L.I., C.P. Baker, L. Kruger and J.E. Rose: Effects of heavy, ionizing, monoenergetic particles on the cerebral cortex. I. Production of laminar lesions and dosimetric considerations. J. comp. Neurol. 115, 219–242 (1960).
Maxwell, D.S., and L. Kruger: Electron microscopy of radiation induced laminar lesions in the cerebral cortex of the rat. 2nd Int. Symp. In: The Response of the Nervous System to Ionizing Radiation, T. Haley (Ed.), Little, Brown & Co., pp. 54–83 (1964).
—: Small blood vessels and the origin of phagocytes in the rat cerebral cortex following heavy particle irradiation. Exp. Neurol. 12, 33–54 (1965).
—: The fine structure of astrocytes in the cerebral cortex and their response to focal injury produced by heavy ionizing particles. J. Cell. Biol. 25, 141 (1965b).
Mugnaini, E., and F. Walberg: An experimental electron microscopical study on the mode of termination of cerebellar corticvestibular fibres in the cat lateral vestibular nucleus (Deiters' nucleus). Exp. Brain Res. 4, 212–236 (1967).
— and A. Brodal: Mode of termination of primary vestibular fibres in the lateral vestibular nucleus. An experimental electron microscopical study in the cat. Exp. Brain Res. 4, 187–211 (1967 b).
Pease, D.C.: Buffered formaldehyde as a killing agent and primary fixative for electron microscopy. Anat. Rec. 142, 342 (1962).
Rose, J.E., L.I. Malis, L. Kruger and C.P. Baker: Effects of heavy, ionizing, monoenergetic particles on the cerebral cortex. II. Histological appearance of laminar lesions and growth of nerve fibers after laminar destructions. J. comp. Neurol. 115, 243–296 (1960).
Szentágothai, J., J. Hamori and Th. Tömböl: Degeneration and electron microscope analysis of the synaptic glomeruli in the lateral geniculate body. Exp. Brain. Res. 2, 283–301 (1966).
Walberg, F.: Role of normal dendrite in removal of degenerating terminal boutons. Exp. Neurol, 8, 112–124 (1963).
—: The fine structure of the cuneate nucleus in normal cats and following interruption of afferent fibres. An electron microscopical study with particular reference to findings made in Glees and Nauta section. Exp. Brain Res. 2, 107–128 (1966).
Westman, J.: The lateral cervical nucleus in the cat. III. An electron microscopical study after transection of spinal afferents. Exp. Brain Res. 7, 32 (1969).
Author information
Authors and Affiliations
Additional information
Supported by research grants from the United States Public Health Service, NB-4578 and NB-6594.
Rights and permissions
About this article
Cite this article
Kruger, L., Hamori, J. An electron microscopic study of dendritic degeneration in the cerebral cortex resulting from laminar lesions. Exp. Brain Res. 10, 1–16 (1970). https://doi.org/10.1007/BF00340516
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00340516