Summary
Due to the bundling of apical dendrites throughout laminae IV-II of the cerebral cortex, two compartments of neuropil are distinguished: (1) the neuropil of the dendrite bundles consisting of closely associated, vertically oriented apical dendrites of pyramidal cells and the fine cell processes between them and (2) the neuropil separating the dendrite bundles. The aim of the present study is to obtain more information concerning differences in composition and arrangement of fine cell processes in the two compartments and to quantify differences in the configuration and size of the extracellular space. To this end, a comparative stereological study of the two compartments has been performed in the upper half of lamina II/III in the visual cortex of 8 adult rabbits. The various constituent elements of the neuropil have been evaluated in electron micrographs with respect (a) to their volume fractions and (b) to their surface fractions, i.e. the surface areae of their membranes comprised in a given volume of tissue. It was found that the volume fractions of thin axons, glial processes and spines are significantly higher between than within dendrite bundles, whereas the volume fraction of dendrites is about 50% higher in the compartment of the bundles. However, when excluding the dendrites in both compartments from calculations, the composition of the remaining neuropil within and between dendrite bundles was found to be identical. As far as surface fractions are concerned, significant differences were shown to exist for all kinds of cell processes except dendrites and myelinated axons. Surface fractions of small axons, glial processes and spines are higher between than within dendrite bundles. The same is true for the surface density of membranes if all kinds of processes are taken together. These findings indicate that the extracellular space between dendrite bundles is considerably more tortuous than that within bundles. Calculation reveals that between dendrite bundles the volume fraction of the extracellular space is about 32% higher than within the bundles.
Similar content being viewed by others
References
Bourke RS, Greenberg ES, Tower DB (1965) Variation of cerebral cortex fluid space as a function of species brain size. Am J Physiol 208:682–692
Detzer K (1976) Course and distribution of apical dendrites of layer V pyramids in the barrel field and area parietalis of the mouse. Anat Embryol 149:251–258
Fleischhauer K (1974) On different patterns of dendritic bundling in the cerebral cortex of the cat. Z Anat Entw Gesch 143:115–126
Fleischhauer K, Laube A (1979) Supracellular patterns in the cerebral cortex. In: Speckmann E-J, Caspers H (eds) Origin of cerebral field potentials. Georg Thieme, Stuttgart, pp 1–12
Fleischhauer K, Petsche H, Wittkowski W (1972) Vertical bundles of dendrites in the neocortex. Z Anat Entw Gesch 136:213–233
Fleischhauer K, Zilles K, Schleicher A (1980) A revised cytoarchitectonic map of the neocortex of the rabbit (Oryctolagus cuniculus). Anat Embryol 161:121–143
Foh E, Haug H, König M, Rast A (1973) Quantitative Bestimmung zum feineren Aufbau der Sehrinde der Katze, zugleich ein methodischer Beitrag zur Messung des Neuropils. Microscop Acta 75:148–168
Globus A, Scheibel AB (1967) Synaptic loci on visual cortical neurons of the rabbit: the specific afferent radiation. Exp Neurol 18:116–131
Hoeltzell PB, Dykes RW (1979) Conductivity in the somatosensory cortex of the cat — evidence for cortical anisotropy. Brain Res 177:61–82
Horstmann E, Meves H (1959) Die Feinstruktur des molekularen Rindengraues und ihre physiologische Bedeutung. Z Zellforsch 49:569–604
Ito S, Winchester RJ (1963) The fine structure of the grastric mucosa in the bat. J Cell Biol 16:121–143
Karlson U, Schultz R (1964) Plasma membrane apposition in the central nervous system after aldehyde fixation. Nature 201:1230–1231
Levin VA, Fenstermacher JD, Clifford SP (1970) Sucrose and inulin space measurements of cerebral cortex in four mammalian species. Am J Physiol 219:1528–1533
Lux HD, Heinemann U, Dietzel I (1986) Ionic changes and alterations in the size of the extracellular space during epileptic activity. Adv Neurol 44:619–639
Meyer G (1987) Forms and spatial arrangement of neurons in the primary motor cortex of man. J Comp Neurol 262:402–428
Nicholson Ch, Freeman JA (1975) Theory of current sourcedensity analysis and determination of conductivity tensor for anuran cerebellum. J Neurophysiol 38:356–368
Nicholson Ch, Phillips JM (1981) Ion diffusion modified by tortuosity and volume fraction in the extracellular environment of the rat cerebellum. J Physiol 321:225–257
Nicholson Ch, Phillips JM, Gardner-Medwin AR (1979) Diffusion from an iontophoretic point source in the brain: role of tortuosity and volume fraction. Brain Res 169:580–584
Palay S, Chan-Palay V (1974) Cerebellar cortex. Springer, Berlin Heidelberg New York
Peters A, Palay SL, Webster HF (1976) The fine structure of the nervous system: the neurons and supporting cells. WB Saunders Company, Philadelphia London Toronto
Peters A, Walsh TM (1972) A study of the organization of apical dendrites in the somatic sensory cortex of the rat. J Comp Neurol 144:253–268
Rappelsberger P, Pockberger H, Petsche H (1981) Current source density analysis: methods and application to simultaneously recorded field potentials of the rabbit's visual cortex. Pflügers Arch 389:159–170
Rappelsberger P, Pockberger H, Petsche H (1982) The contribution of the cortical layers to the generation of the EEG: field potential and current source density analyses in the rabbit's visual cortex. Electroencephalogr Clin Neurophysiol 53:254–269
Schleicher A, Zilles K, Kretschmann H-J (1975) Eine Methode zur rationellen Partikelzählung. Microscop Acta 77:37–47
Schmolke C (1987) Morphological organization of the neuropil in lamina II–V of rabbit visual cortex. Anat Embryol 176:203–212
Schmolke C, Fleischhauer K (1984) Morphological characteristics of neocortical laminae when studied in tangential semithin sections through the visual cortex of the rabbit. Anat Embryol 169:125–132
Schmolke C, Viebahn C (1986) Dendrite bundles in lamina II/III of the rabbit neocortex. Anat Embryol 173:343–348
Schultz RL, Karlson UL (1972) Brain extracellular space and membrane morphology variations with preparative procedures. J Cell Sci 10:181–195
Sitte H (1967) Morphometrische Untersuchungen an Zellen. In: Weibel ER, Elias H (eds) Quantitative methods in morphology. Springer, Berlin Heidelberg New York, pp 167–198
Uylings HBM, Smit GJ (1975) Three-dimensional branching structure of pyramidal cell dendrites. Brain Res 87:55–60
Van Harreveld A (1972) The extracellular space in the vertebrate central nervous system. In: Bourne GH (ed) The structure and function of nervous tissue, Vol IV. Academic Press, New York London, pp 447–511
Van Harreveld A, Khattab FI (1968) Perfusion fixation with glutaraldehyde and post-fixation with osmium tetroxide for electron microscopy. J Cell Sci 3:579–594
Watanabe Y, Haug H (1980) The quantitative analysis of the neuropil in the visual cortex of the kitten. Mikroskopie 37:213–219
Weibel ER (1979) Stereological methods, Vol 1. Practical methods for biological morphometry. Academic Press, London
Weibel ER, Elias H (1967) Introduction to stereology and morphometry. In: Weibel ER, Elias H (eds) Quantitative methods in morphology. Springer, Berlin Heidelberg New York, pp 1–19
Zunino G (1909) Die myeloarchitektonische Differenzierung der Großhirnrinde beim Kaninchen (Lepus cuniculus). J Psychol Neurol 14:38–70
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Schmolke, C., Schleicher, A. Structural inhomogeneity in the neuropil of lamina II/III in rabbit visual cortex. Exp Brain Res 77, 39–47 (1989). https://doi.org/10.1007/BF00250565
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00250565