Cortical gyrification in the rhesus monkey: a test of the mechanical folding hypothesis

A quantitative measure of the degree of cortical folding was used to test the mechanical hypothesis of cortical folding and to analyze structural properties of the rhesus monkey cortex. The rhesus monkey cortex has both its maximal degree of cortical folding and the largest ratios of supragranular laminae to the lower granular and infragranular layers in the caudal cortex, over the posterior parietal-anterior occipital regions. Low values for cortical folding and for the ratios of inner and outer cortical layers characterize frontal regions. Topographically intermediate regions are intermediate in both sets of values. Ratios of the amounts of white and gray matter have a topographic pattern that differs from those of cortical folding, suggesting that the sizes of subcortical axonal bundles are not directly associated with the degree of cortical folding. Whereas differences in mean degrees of cortical folding are correlated with brain weights among species of primates, the amount of folding is not associated with brain weight within the species.

Developmental gradients of vasoactive intestinal polypeptide (VIP)-containing neurons in the rat visual cortex detected by image analysis

The postnatal development of vasoactive intestinal polypeptide-immunoreactive (VIP-IR) neurons was followed by computer-assisted image analysis in the rat visual cortex. The laminar distribution of all VIP-IR structures was measured. These structures were subdivided into cell somata, dendritic profiles and axonal boutons and measured separately. VIP-IR neurons were first seen on postnatal day 1, mostly in the upper half of the presumptive visual cortex. A localization of cell bodies similar to that in the adult is reached between days 12 and 16. VIP-IR dendrites have a protracted growth period as compared to perikarya, involving a developmental gradient from an even distribution to a concentration in the upper cortical layers. This is due to the formation of dendritic terminal arbors after the second postnatal week. Scattered VIP-IT axonal boutons appear on day 3 in the midportion of the presumptive visual cortex. Their typical laminar distribution in layers II, IV and lower VI was observed after day 12. Our results suggest that the biochemically detected sharp increase in VIP levels after the second postnatal week is due to the maturation of cell processes as a morphological basis of neuronal connectivity.

Mapping of glial fibrillary acidic protein-immunoreactivity in the rat forebrain and mesencephalon by computerized image analysis

Computer-assisted image analysis was used to map the regional distribution of glial fibrillary acidic protein-immunoreactive (GFAP-IR) astrocytes in the rat forebrain and mesencephalon. A complete survey of packing densities of GFAP-IR structures was performed. Computer maps revealed high values in the outer and inner layers of the cortex, some hippocampal and olfactory bulb layers, prepiriform cortex, dorsal part of the caudate-putamen, globus pallidus, lateral septum, reticular thalamic nucleus, lateral habenular nucleus, circumventricular organs, nuclei of the medial hypothalamus, substantia nigra, interpeduncular nucleus, and mamillary body. These correspond to regions of the embryonic pial and ventricular brain surfaces, which undergo developmental alterations including growth and various forms of internalization. From this we conclude that in the adult brain, astrocytes of high GFAP-IR are derivatives of surface-contact glia, whereas those located in areas having developed by the local thickening of the neural tube wall show reduced or no GFAP-IR.

Postnatal development of forebrain regions in the autoimmune NZB-mouse. A model for degeneration in neuronal systems

NZB-mice are known to have impaired cognitive functions. The aim of the present study is the analysis of the volume growth of different brain regions in NZB/NBOM-mice, because the functional impairment increases postnatally. The regions analysed include brain structures which are important for learning and memory functions. The comparison between NZB-mice and controls (CFW- and Balb/c-mice) shows that the hippocampal volume in NZB-mice is larger than in controls. However, ectopic neurons are found in the dentate gyrus of NZB-mice, indicating a changed connectivity in this region. The septum and the amygdala show no difference in volume in NZB-mice compared to controls. The adult volume of the entorhinal cortex of the NZB-mice is the smallest of the three strains. The development of this brain region is characterized by an overshooting growth in all strains. The caudate-putamen complex and the globus pallidus of NZB-mice undergo a reduction in volume during the postnatal period. This is not found in the controls. An overshooting growth is seen in the mamillary bodies of the three strains, and in the anterior thalamic nucleus of NZB-mice. However, only the NZB-mice show a prolonged reduction of the volume of the mamillary bodies, which is not finished during the observed time period. Both regions are important relay stations in the Papez-circuit, a neuronal system associated with learning and memory functions. The prolonged postnatal reduction in volume of the mamillary bodies and the anterior thalamic nucleus of NZB-mice may be the structural correlate of the impaired cognition and memory in this strain.

Nicotinic cholinoceptive neurons of the frontal cortex are reduced in Alzheimer's disease

The cellular distribution of nicotinic acetylcholine receptors was studied in the frontal cortex (area 10) of 1) Alzheimer patients and compared to 2) age-matched and 3) middle-aged controls using the monoclonal antibody WF 6 and an immunoperoxidase protocol. Statistical analysis revealed significant differences between the number of labeled neurons among all three groups tested (middle-aged controls greater than aged controls greater than Alzheimer cases). No differences were seen for cresyl violet-stained samples. These findings underline that the nicotinic receptor decrease found with radioligand binding may reflect a postsynaptic in addition to a presynaptic component.

Local cerebral glucose utilization in the brain of old, learning impaired rats

The local cerebral glucose utilization (LCGU) was measured in 63 different cortical areas and nuclei of the telencephalon, diencephalon and rhombencephalon of young adult (3 to 4-month-old) rats and of 27-month-old Wistar rats, in which learning impairments had been proven by a water maze test. The LCGU was determined by [14C]2-deoxyglucose autoradiography. In the old rats the mean LCGU of all brain regions was significantly reduced by about 10% compared with the young control group; the mean LCGU was 74.2 mumol glucose/(100 g x min) in the young and 66.7 in the old rats. Different degrees of LCGU decrease were found in the different regions. Most of the brain regions with significantly reduced LCGU values in the aged, learning impaired rats were associated with auditory and visual functions, the dopaminergic system, and structures known to be involved in learning and memory processes. Therefore, the regional pattern of LCGU reduction found in the aged, learning impaired rats did not resemble any known pattern found after lesions of a single transmitter system or systemic administration of transmitter agonists or antagonists.

An immunochemical quantitative analysis of the protein pattern in physiologic and pathologic vitreous

Biochemical changes in the vitreous in different vitreoretinal disorders have not yet been thoroughly studied. Using enzyme-linked immunosorbent analysis (ELISA), we established mean values and 95% confidence intervals for six proteins of physiologic human vitreous: albumin (293 +/- 18 mg/l), transferrin (73.7 +/- 6.6 mg/l), immunoglobulin G (IgG), (33.5 +/- 3 mg/l), alpha 1-antitrypsin (14.1 +/- 2.9 mg/l), alpha 1-acid glycoprotein (4 +/- 0.7 mg/l), and lactoferrin (less than 50 micrograms/l). These six proteins were also determined in vitreous aspirates from patients with idiopathic proliferative vitreoretinopathy (n = 10), traumatic proliferative vitreoretinopathy (n = 10), and proliferative diabetic retinopathy (n = 15). The pattern of protein levels varied widely within each of the disorders. An analysis of absolute protein levels showed significant differences in total protein and alpha 1-antitrypsin levels between controls and pathologic vitreous samples. We observed differences in transferrin between controls and proliferative diabetic retinopathy (PDR), and differences in alpha 1-acid glycoprotein between controls and both types of proliferative vitreoretinopathy (PVR). The single disorders themselves could not be differentiated by any of the proteins. When the relative contribution of single proteins to total vitreal protein was compared, albumin was lower in all three disorders than in controls. Transferrin was lower in traumatic PVR than in controls, in PDR, or in idiopathic PVR. Our results indicate that the three vitreoretinal disorders studied are characterized by a breakdown of blood-ocular barriers.

Distribution of glial fibrillary acidic protein and vimentin immunoreactivity during rat visual cortex development

The postnatal maturation of astrocytes in the rat visual cortex was analysed by immunostaining the astroglial proteins vimentin and glial fibrillary acidic protein with poly- and monoclonal antibodies. Vimentin immunoreactivity was present in the visual cortex up to the third postnatal week, whereas immunolabelling first disappeared in the cortical layers and then in the white matter. In the early postnatal period, vimentin antibodies labelled radial glial fibres. After the first postnatal week staining of radial glial fibres gradually disappeared and vimentin immunoreactivity was localized in a few protoplasmic astrocytes in the grey matter and fibrous astrocytes in the white matter. The development of glial fibrillary acidic protein-positive astrocytes was not fully complete until postnatal day 50. Glial fibrillary acidic protein-positive radial glial fibres were present after birth and disappeared towards the end of the third postnatal week. Staining of astrocytes in the white matter and in cortical layers I and VI reached an adult density at postnatal days 8 and 20, respectively. A progressively later development of glial fibrillary acidic protein-positive astrocytes was observed in cortical layers II-V which was completed between postnatal days 47 and 50. In the adult rat visual cortex glial fibrillary acidic protein-positive astrocytes were especially dense in layers I and VI, moderate in layers II/III and V and nearly absent in layer IV and lower layer III. The time course of the loss of vimentin and the gradual appearance of glial fibrillary acidic protein immunoreactivity in the visual cortex is considered as an index of astrocytic maturation and the spatiotemporal sequence of this maturation pattern is discussed in terms of reciprocal neuron-astrocyte interactions during brain development.

Encephalization in hummingbirds (Trochilidae)

The brain mass in 23 hummingbird species was compared to that in galliform birds taking body mass into consideration. Hummingbird brain masses were determined by endocranial volumes, and their body masses were calculated from skeletal measurements. Galliform data were taken from a recent publication. Hummingbirds have brains that are approximately 2.5 times larger than those of galliform birds. Such encephalization may be due to (1) an enlargement of the telencephalon, or (2) an enlargement of functionally well-defined extratelencephalic brain parts. Based on the extremely specialized feeding behavior of the nectarivorous hummingbirds and the neurological demands associated with sucking nectar during hovering, the second hypothesis is better supported, but further studies are needed.

Regional and laminar distributions of alpha 1-adrenoceptors and their subtypes in human and rat hippocampus

The distributions of the alpha 1-adrenoceptor and its subtypes (alpha 1A and alpha 1B) in human and rat hippocampus are analysed by quantitative receptor autoradiography. alpha 1-Adrenoceptors are labelled by [3H]prazosin. The alpha 1A subtype is visualized by [3H]prazosin after irreversible blockade of alpha 1B adrenoceptors with chloroethylclonidine or directly by [3H]5-methyl-urapidil. The alpha 1B subtype is investigated by [3H]prazosin binding in the presence of the alpha 1A antagonist 5-methyl-urapidil. Considerable differences in the regional and laminar patterns of alpha 1-adrenoceptors are found between rat and human hippocampi. The rat hippocampus is characterized by a low overall density and a rather homogeneous regional and laminar distribution. This is in contrast to the human pattern, which shows a much higher overall level of alpha 1 receptor density and a restriction of alpha 1 receptors to the CA3 region of Ammon's horn and the dentate gyrus. Moreover, alpha 1A and alpha 1B receptors of the human hippocampus are differentially distributed with the alpha 1A subtype concentrated in the hilus and lucidum layer of CA3, and the alpha 1B subtype concentrated in the molecular layer of the dentate gyrus. Additionally, the distribution of alpha 1 receptors is compared with the distribution of 5-hydroxytryptamine 1A receptors. The subtype specific pattern is correlated with the distribution of glutamatergic systems in the human (but not in the rat) hippocampus. alpha 1A Receptor localization coincides with the target area of the mossy fibre system, and alpha 1B receptors are preferentially localized in the target area of the hippocampal associational fibres and partly of the perforant pathway. This result points to possible interactions between noradrenaline- and glutamate-mediated neurotransmission differentiated by topographically segregated alpha 1-adrenoceptor subtypes.

Quantitative autoradiography of 11 different transmitter binding sites in the basal forebrain region of the rat--evidence of heterogeneity in distribution patterns

The distribution of 12 different binding sites for acetylcholine, L-glutamate, GABA, 5-hydroxytryptamine, dopamine and noradrenaline was measured with quantitative receptor autoradiography in four regions of the rat basal forebrain (medial septal nucleus including vertical and horizontal limbs of the diagonal band of Broca, magnocellular preoptic nucleus, substantia innominata and basal nucleus of Meynert, ventral pallidum). L-Glutamate binding sites represent the largest portion of the analysed receptors in all regions, followed by muscarinic2, 5-hydroxytryptamine1 and GABAA receptors. Muscarinic1, dopamine1, dopamine2 and 5-hydroxytryptamine2 receptors and alpha 1-, alpha 1A- and alpha 1B-adrenoceptors represent the minor receptor populations. The largest portion of the dopamine receptors is represented by the dopamine1 subtype, and the alpha 1B subtype dominates the alpha 1-adrenoceptor group. A heterogeneity of the distribution patterns of the different receptors throughout the basal forebrain regions is found. A comparison of the patterns shows that alpha 1-adrenoceptors have a similar regional distribution to that of the muscarinic2 receptors, but both receptor types have reciprocal distributions compared with the 5-hydroxytryptamine1 receptors. The results indicate that one transmitter may exert different effects in the basal forebrain regions depending on the densities of the respective receptor subtypes. Moreover, similar or reciprocal distribution patterns of some, but not all, analysed receptors point to a non-random association (co-distribution) of the different transmitter systems in the basal forebrain regions.

Parallel evolution in mammalian and avian brains: comparative cytoarchitectonic and cytochemical analysis

Comparative morphology, which is based on the selection theory of evolution, analyses the impact of function upon structure and, therefore, emphasizes the adaptive events and biological advantage during the evolution of organs. A comparison based on analogies is described here as an adequate method. The hypothesis is proposed that the evolution of the brain follows the same trends in birds as in mammals. This hypothesis is proved by (1) allometric studies of brain weight and brain structure volume in relation to body weight in mammals and birds; (2) architectonic studies using image analysis on cell and fibre stains as well as on histochemical preparations and receptor autoradiography; and (3) hodological studies with injections of [3H]leucin, HRP and WGA-HRP. The results reveal a vast amount of structural and functional similarities in avian and mammalian brain organization, especially an expansion of structures that permit multimodal integration capacity in the telencephalon. Thus, a parallel evolution occurred in these two groups of vertebrates. It is argued that this may be a general phenomenon in evolution. A cladistic approach, which is based on the concept of homologies (plesio-, apomorphies), pushes aside the existence of analogies. For this reason, cladism does not seem to be a method to answer questions of evolutionary morphology adequately.

Quantitative development of brain and brain structures in birds (galliformes and passeriformes) compared to that in mammals (insectivores and primates)

The brain weight and brain structure volumes of galliform and passeriform birds were calculated and related to body weight. The total brains and 14 brain regions were investigated in order to calculate factors by which these structures in passeriforms exceed those in galliforms in size. The larger passeriform brains have larger telencephala, especially ventral hyperstriata and neostriata. The enlargement of total brain and telencephalon resembles that in primates, compared to insectivores, within mammals. The enlargement of the ventral hyperstriata + neostriata in passeriforms is fundamentally similar to that of the isocortex in mammals: it reflects an expansion of multimodal integrational capacities, as the ventral hyperstriatum and neostriatum are occupied exclusively or primarily by multimodal integrational areas as is the isocortex.

A new method for quenching correction leads to revisions of data in receptor autoradiography

Differential quenching of beta-emission affects strongly the analysis of receptor distribution patterns in quantitative receptor autoradiography with tritiated ligands. Different methods for the quenching correction have been described in the past, but some of these are of limited value, if a detailed anatomical parcellation is necessary. Other methods correct exclusively local variations in lipid concentration, which is an important, but only one of several factors causing quenching. A new method for the measurement of quenching (or autoradiographic efficiency) is presented, which permits an anatomically detailed and direct determination of the total quenching without lipid extraction procedures. This method is based on the measurement of autoradiographic efficiency in cryostat sections homogeneously labeled with tritiated formaldehyde by an underlying gelatine section containing this labeled compound. Regional and layer specific measurements of autoradiographic efficiency in cortical and subcortical regions of the human and rat brain are reported. A significant correlation was found between the density of myelin and autoradiographic efficiency but other factors were also shown to influence differential quenching. The use of the here presented correction procedure leads to revisions of the laminar distribution patterns reported for different receptors in human and rat cortical areas. Our results show, that a complete quenching correction is necessary for the mapping of receptor distributions with tritiated ligands.

Ultrastructure of PkC(II/III)-immunopositive structures in rat primary visual cortex

In the primary visual cortex of adult rats the cellular and subcellular distribution of protein kinase C isozymes II and III (PkCII/III) was examined by immunohistochemical methods with a monoclonal antibody against PkCII/III. Strong PkC(II/III)-immunoreactivity was found in neurons and astrocytes. Immunopositive neurons exhibited morphological features characteristic for both pyramidal and non-pyramidal cells. They were distributed in layers II through VI but were concentrated in layers II/III. At the electron microscopic level immunoprecipitate was found predominantly in distinct regions of the somata, except the nuclei, and only a few labeled dendrites and axons were seen. Two different patterns of cytoplasmic immunoreactivity could be distinguished. In most neurons, PkC(II/III)-staining was confined to cytoplasmic spots associated with the Golgi complex, while a few neurons exhibited additional labeling in the vicinity of the cell membrane. Moreover, PkC(II/III)-immunoreactivity was present in numerous astroglial processes and in the perikaryal cytoplasm of a subpopulation of astrocytes. The present data provide morphological indications for specific functions of PkC isozymes II and III in neurons as well as in astrocytes.

Vasoactive intestinal polypeptide (VIP) containing cells in the developing rat occipital hemisphere

Numerous cells were observed to show intense vasoactive intestinal polypeptide (VIP) immunoreactivity from birth to postnatal day 8 in the subventricular zone of the rat occipital hemisphere. This cell population was markedly reduced by postnatal day 8, but isolated clusters of VIP cells persisted into adulthood. In addition, long, L-shaped VIP fibers were seen in the hemispheric wall up to postnatal day 16, but not in the adult. Parallel to the reduction in number of the subventricular VIP cells an increasing number of VIP cells appeared in the neo- and allocortex, developing by postnatal day 12 all the features of the mature cortical bipolar fusiform neurons. As possible alternatives, the migration of subventricular VIP cells into the cortex, the transient character of the subventricular VIP population or the expression of VIP by radial glia are discussed.

Local cerebral glucose utilization in the neocortical areas of the rat brain

The neocortex of the rat brain can be subdivided into regions of different local cerebral glucose utilization (LCGU). However, only a few neocortical areas can be delineated by differences in mean LCGUs between neighbouring areas. These area borders correspond exactly with cytoarchitectonically defined borders found in adjacent Nissl-stained preparations. On the other hand, nearly all of the architectonically defined area borders are also recognizable in the LCGU pictures, if differences in laminar distribution patterns of LCGU are taken into account. Furthermore, interareal differences in mean LCGU mainly reflect changes in layer IV, whereas layers II-III and V-VI show nearly identical LCGU values in all neocortical areas of the rat brain. The primary sensory areas exhibit the highest LCGU in layer IV, while the primary motor cortex shows a high LCGU in layer V. As the cytoarchitectonically defined pattern of the cortex is generally corroborated by the regional and laminar LCGU distribution, anatomical, metabolic and functional aspects of cortical architecture are associated.

Immunocytochemical visualization of muscarinic cholinoceptors in the human cerebral cortex

The monoclonal antibody M 35 was used to study the cellular and subcellular distribution of muscarinic acetylcholine receptors in the human cerebral cortex. M35, raised against purified muscarinic receptor protein, exerts muscarinic agonist-like effects at cholinergic synapses. Applied to human cortical tissue immediately fixed upon neurosurgical removal, light microscopically M 35 revealed immunoreactive perikarya predominantly of the pyramidal cell type in layers II/III and V, their labeled apical dendrites extending into the superficial layers. Furthermore, immunoprecipitate decorated distinct regions of the perikaryal cytoplasm, numerous dendritic profiles and synapses of both symmetric and asymmetric appearance. In the perikarya immunoprecipitate was associated with ribosomes, the endoplasmic reticulum and the Golgi apparatus. In dendrites the microtubular system, in synaptic complexes the postsynaptic membranes were decorated. The results suggest that novel informations about the cell type specific and subcellular distribution of human muscarinic cholinoceptors can be obtained by M 35 immunocytochemistry.

Quantitative analysis of the retrograde reaction of motoneurons with an image analyser

The neuronal profiles of cell bodies in the facial nerve nucleus of adult rats were measured after partial peripheral nerve transsection. An image analyser was used for automatic recognition and morphometry. Based on classification of the neuronal profiles described in a previous paper, a morphometrical study was performed in order to analyse structural aspects of the retrograde reaction in quantitative terms. Beside the quantification of classical features of retrograde reaction (chromatolysis; nuclear eccentricity; increased basophilia; perikaryal, nuclear and nucleolar swelling), several reactive changes so far not recognized (karyoplasmic basophilia and granulation) were detected. These changes were interpreted as morphological correlates of regeneration in retrogradely reacting cells.

Image analysis of Nissl-stained neuronal perikarya in the primary visual cortex of the rat: automatic detection and segmentation of neuronal profiles with nuclei and nucleoli

An image analysing procedure for the morphometric characterization of cortical neurons in Nissl-stained brain sections is described. It consists of the automatic detection of cellular profiles and their compartments: cytoplasm, nucleus and nucleolus. The algorithm was designed to cope with the large morphological spectrum of cortical perikarya (e.g. geometrical properties of perikarya, staining intensities of cell compartments and nucleo-plasmic area-ratio) including pyramidal (Golgi-category I) and non-pyramidal (Golgi-category II) neurons. Clusters of cells were separated and non-neuronal structures (e.g. glia, endothelial cells) as well as tangential, non-nucleolated sections through neuronal perikarya recognized and excluded from further analysis without requiring interactive procedures. The performance of the profile recognition procedure was evaluated using 426 nucleolated and non-nucleolated profiles of different types of neurons in the primary visual cortex of the rat. Nucleolated profiles were recognized as such with a 91% accuracy, non-nucleolated profiles were rejected correctly in 90% of cases. After automatic segmentation and selection of nucleolated neuronal profiles from the microscopic field, a large set of quantitative morphological features including geometrical, densitometrical and textural parameters can be measured using high power light microscopy. This permits quantitative morphometric characterization of different neuronal types. This procedure is the first part of a system for the automatic classification of Nissl-stained cortical neurons.

A quantitative approach to cytoarchitectonics: analysis of structural inhomogeneities in nervous tissue using an image analyser

Cytoarchitectonic investigations are based on the analysis of structural inhomogeneities in the neuronal composition of nervous tissue. Boundaries of brain regions are established at locations where local structural properties, such as density, shape, orientation or arrangement of the nerve cells, change. A quantitative approach requires a complete scanning of histological sections and the measurement of at least one of these properties using an automatic device. In contrast to recently developed stereological methods which result in unbiased estimates of parameters and which are based on efficient sampling procedures, measurements with automatic devices are biased due to section thickness and problems in the segmentation of nerve cell bodies. Automatic measurements are necessary, however, if a complete scanning of histological sections is required in order to localize areal or laminar boundaries. In this approach, the grey level index (GLI) is measured with a TV-based image analysing system from routine histological sections. Using Nissl-staining, this parameter is a biased estimate of the local volume density of Nissl-positive structures (cell bodies). The histological section is digitized into a GLI image by a scanning procedure. The GLI image is processed by image enhancement procedures in order to visualize the laminar pattern. Areal boundaries are localized at positions where this laminar pattern changes. GLI statistics of single brain regions can easily be evaluated by delineating these regions with a cursor in the GLI images of the sections. Information from a series of sections is compiled by specific application programs.

Remote astrocytic response as demonstrated by glial fibrillary acidic protein immunohistochemistry in the visual cortex of dorsal lateral geniculate nucleus lesioned rats

The reaction of astroglia was investigated after unilateral destruction of the dorsal lateral geniculate nucleus in the primary visual cortex of adult albino rats. The destruction of the dorsal lateral geniculate nucleus was performed by stereotaxic injections of ibotenic acid, and the location was verified in Nissl stained sections in each animal. Electron microscopic observations demonstrated the presence of degenerating axon terminals surrounded by hypertrophic astroglial processes mainly in layers III and IV of the ipsilateral primary visual cortex. The ipsilateral (impaired) and contralateral (control) sides of the primary visual cortex showed light microscopically a clearly differing appearance and distribution of glial fibrillary acidic protein (GFAP) immunoreactivity 7 to 11 days after the unilateral injection of ibotenic acid into the dorsal lateral geniculate nucleus. Whereas the control side of the primary visual cortex showed GFAP staining only in the subpial zone of layer I and close to the white matter, all layers of the impaired cortex showed an intense GFAP immunoreactivity. The increase in immunoreactivity was confined to the primary visual cortex. The extent of and increase in immunoreactivity was corroborated by image analysis. These findings were interpreted as a localized hypertrophy of astroglia caused by the anterograde degeneration of geniculocortical terminals. This hypertrophy is accompanied by an increase in GFAP, which may represent the stabilization of the cytoskeleton of newly formed glial processes involved in the rearrangement of the impaired neuropil.

Recognition of the retrograde reaction in motoneurons using an image analysing system

An automatic procedure is described which allows recognition of sectional profiles of alpha-motoneurons of the facial nucleus of the rat. The system is able to distinguish nucleus and nucleolus from the cytoplasm of the nerve cell profile and to characterize those structures by suitable parameters. The region of the nucleus of the facial nerve (FNN) has been measured 7 days after unilateral partial nerve transsection. Based on the resulting data a multivariate analysis was performed to distinguish between normal and retrograde reacting cells. It is shown that this automatic cell characterisation technique is highly sensitive and reliable. The data were used to describe comprehensively the retrograde reaction of the cell.

Immunohisto- and cytochemical localization of cortical nicotinic cholinoceptors in rat and man

A monoclonal antibody (WF 6) raised against purified Torpedo nicotinic acetylcholine receptor was applied to study the cellular and subcellular receptor distribution in human and rat neocortex. In both species, immunostaining was most prominent in perikarya and dendrites of the projection neurons in layers III and V. In layer VI fusiform cells displayed immunoreactivity while in layers I, II and IV some round-shaped cells were immunostained. Subcellularly, immunoprecipitate was found in neuronal perikarya, dendrites and in the postsynaptic thickenings, indicating intracellular sites of synthesis, transport and membrane incorporation of receptor protein. The results suggest that WF 6-immunocytochemistry is a useful tool to label nicotinic cholinergic receptors rendering new information about the specific cell-type and subcellular receptor distribution hardly obtainable by using conventional receptor autoradiography.

Reactive astrocytes and macrophages in the brain stem of SIDS victims? Eleven age- and sex-matched SIDS and control cases

The investigation was carried out on 11 sudden infant death (SIDS) cases which were compared with age- and sex-matched controls. Six brain nuclei were selected for evaluation. Using immunohistochemical methods, macrophages were selectively demonstrated by detection of lysozyme; reactive astrocytes, by detection of intracytoplasmic albumin (marker of prior impairment of blood-brain barrier function) or GFAP. No lysozyme-positive cells were demonstrable in the brain stem of any of the examined cases. Although a greater number of reactive, GFAP-expressing astrocytes were found in the SIDS cases, 3 of the 11 SIDS cases (compared to 5 controls) had no reactive astrocytes in any of examined brain nuclei. Reactive astrocytes, however, were identified in more than half the controls. Sections treated with anti-albumin serum were evaluated quantitatively. Total number of non-neuronal cells, relative proportion of astrocytes, and proportion of albumin-positive astrocytes were determined. Paired brain nuclei were counted on both sides of the brain stem. The number of non-neuronal cells, astrocytes, and albumin-positive astrocytes in the SIDS cases did not differ significantly from those in the controls. No statistically relevant difference was established between the right and left parts of the brain stem. The findings were discussed in light of the literature.

Cerebral asymmetry: MR planimetry of the human planum temporale

A method is described for the imaging and planimetric measurement of the planum temporale (PT) using computer reformations from three-dimensional fast low angle shot magnetic resonance (MR) data. The procedure allows the determination of size and left-right asymmetry of this area on the posterior supratemporal surface, which has been assumed by previous investigators to be a structural correlate of speech lateralization. To establish a consistent method for future studies, special effort was invested in the elaboration of reliable imaging criteria for the borders of the PT. The authors report MR planimetric measurements of the PT in 10 human cadaver brains performed independently and in a "blinded" fashion by two observers. A high degree of interobserver agreement was found, demonstrating the reliability of the MR criteria for PT delineation. The planimetric data correlated with those from subsequent anatomic measurements following section of the same specimens. The left-right ratios of PT size were almost the same with both methods (mean 1.9). Magnetic resonance planimetry of the PT is a noninvasive, reliable, and quantitative procedure to determine gross cerebral asymmetry in the posterior speech area.

Different metabolic changes in the lateral geniculate nucleus and the superior colliculus of adult rats after simultaneous or delayed double enucleation

By means of the [14C]deoxyglucose method the local cerebral glucose utilization (LCGU) was measured in the lateral geniculate nucleus and the superior colliculus of rats with a simultaneous double enucleation, animals with an enucleation of the right eye between neonatal and adult stages followed by an enucleation of the left eye some months later and adult control rats. The control animals show LCGU values within the limits published by other observers. The LCGU values of the simultaneously double-enucleated rats are reduced on both sides to the same extent by about 20%. The dorsal lateral geniculate nucleus shows the largest decrease. The LCGU values of the rats with the delayed double enucleation have decreased even more (up to 37%). The right sided visual brain regions have a significantly lower LCGU than the corresponding regions on the left side. These findings indicate that unilateral enucleation from neonatal to adult stages leads to adaptive changes resulting in a higher metabolic vulnerability, which is revealed by the second enucleation.

Local cerebral glucose utilization in the autoimmune New Zealand black (NZB) mouse

By means of the [14C]-2-deoxyglucose method the local cerebral glucose utilization (LCGU) was measured in 41 brain regions in autoimmune New Zealand Black (NZB) mice and in Carworth Farm Winkelmann (CFW) mice, which served as the control strain. At the age of 6 months, the mean LCGU of all measured areas and brain stem nuclei was 67.7 mumol glucose/(100 g x min) in the nonautoimmune CFW mice. These LCGU values are within the limits published by other observers. In contrast, in the aged-matched NZB mice the glucose use was markedly reduced, the mean LCGU of all measured areas being 37.7 mumol glucose/(100 g x min). These findings suggest that the immunological, morphological and behavioural abnormalities in the aged NZB mouse correlate with a reduced functional activity of the central nervous system, measured as reduced cerebral glucose utilization.

Cytological investigations on the cerebellar cortex of sudden infant death victims

The study was based on the hypothesis that cerebellar hypoxia may play a role in sudden infant death syndrome resulting in morphological changes of the cerebellar cortex, especially with respect to Purkinje cell density. In the morphological evaluation of the Purkinje cell layer, special consideration was additionally given to secondary alterations (i.e., macrophage and/or astrocyte reaction). A total of 12 sudden infant death syndrome cases were compared with an age- and sex-matched control group. The Purkinje cell density was evaluated by determining the number of these cells per surface unit on parasagittal sections in both hemispheres. The myelomonocytic and glial reaction was demonstrated by immunohistochemical methods using lysozyme as leukocyte and macrophage markers and glial fibrillary acidic protein as an astrocyte marker. Qualitatively, no alterations resembling a macrophage or glial cell reaction were detected in sudden infant death syndrome. No differences between the right and left cerebellar hemisphere could be established in the victims of sudden infant death syndrome nor in the controls. The number of Purkinje cells per 0.352 mm2 cortex was higher in the younger victims of sudden infant death (younger than 45 weeks of gestation) than in all matched controls. A statistically significant difference in Purkinje cell density, however, could not be established, and, especially, no indications of hypoxia were observed in the cerebellar cortex.

Distribution of cholinergic receptors in the rat and human neocortex

Autoradiographic labelling of muscarinic (M1, M2, NMS binding sites) and nicotinic receptors shows an inhomogeneous distribution over architectonically identified cortical areas of the rat brain with highest concentrations in the medial prefrontal and frontal areas. Beside this general trend the areal patterns of different receptors are slightly varying. The laminar distribution of these receptors in the rat and human neocortex is characterized by two different patterns, one with highest receptor densities in the supragranular layers (M1 receptors, NMS binding sites), the other with a preferential labelling of layer IV and (with a lower intensity) layer V (M2 and nicotinic receptors). M1 receptors and NMS binding sites are codistributed at the laminar level with each other and with GABAA, D1, 5-HT1 and glutamate receptors; M2 receptors are codistributed only with nicotinic receptors. Immuno-histochemical studies with antibodies against muscarinic and nicotinic receptors demonstrate that these structures occur mainly in pyramidal and spiny stellate cells and to a lesser extent (13%) in a variety of interneurons. The immunoreactivity is visible in the perikaryon, dendrites and postsynaptic membranes. Neurons are found in the human neocortex, which react exclusively with one of the two antibodies, but a fraction of the neurons (about 30%) contains antigenic sites reacting with both antibodies. This is interpreted as colocalization of nicotinic and muscarinic receptors in some cortical neurons.

Human cortical neurons contain both nicotinic and muscarinic acetylcholine receptors: an immunocytochemical double-labeling study

Using immunofluorescence histochemistry, in the human cerebral cortex neurons immunoreactive for both nicotinic and muscarinic acetylcholine receptor proteins could be demonstrated. Vibratome sections of biopsy and autopsy specimens of human temporal and occipital lobes were incubated with monoclonal antibodies specific for muscarinic (M 35) and nicotinic (WF 6) acetylcholine receptor protein. Immunoreactive sites were visualized using a biotin-streptavidin-phycoerythrin system (M 35, red fluorescence) and fluorescein-conjugated immunoglobulins (WF 6, green fluorescence). Immunofluorescence of both antibodies was preponderant in pyramidal neurons located in layers II/III and V and their apical dendrites. Some round and ovoid immunolabeled cells were encountered in layers VI and IV. About 30% of the cholinoceptive cortical neurons, in particular the pyramidal cells, displayed immunoreactivity for both receptor types. The present investigation shows a subpopulation of human cortical neurons to contain both nicotinic and muscarinic receptors. The coexistence of acetylcholine receptors may provide the morphological basis of simultaneous impact of acetylcholine on both receptor types in the same neuron of the human cerebral cortex.

Gyrification in the cerebral cortex of primates

The degree of cortical folding in primates has been analyzed using a gyrification index (GI). Correlation analyses of the GI with body weight, brain weight and neopallial volume show that the human data fit the general trend of the nonhuman anthropoids. Bigger primate brains exhibit a higher degree of fissurization, but a taxonomic difference that is independent of brain weight between prosimians and anthropoids has also been observed. In these regressions, anthropoids differed from prosimians by having a larger increase in gyrification for every unit increase in body or brain weight or neopallial volume. A stepwise regression also shows a prosimian-anthropoid difference. The best predictor for convolutedness in anthropoids is neocortical volume, while in prosimians it is brain weight. The GI in catarrhines is correlated with total sulcal length but not number of sulci. This result suggests paleontological studies of total sulcal length can give direct information on the evolution of cortical folding in primates.

The human pattern of gyrification in the cerebral cortex

The degree of cortical folding found in adult human brains has been analyzed using a gyrification index (GI). This parameter permits the description of a mean value for the whole brain, but also a local specific analysis of different brain regions. Correlation analyses of the GI with age, body weight, body length, brain weight and volume of the prosencephalon and the cortex show no significant results. GI values do not differ significantly between male and female brains, right and left hemispheres or right and left sides of the superior temporal plane. The GI shows maximal values over the prefrontal and the parieto-temporo-occipital association cortex. A comparison between the rostro-caudal GI patterns of human brains and those of prosimians and Old World monkeys shows the largest difference over the prefrontal cortex. The mean GI increases from prosimians to human brains with the highest values for non-human primates being in the pongid group.

Cytokinetics of epidermic cells in skin from human cadavers. II. Dependency on sex, age, and site

Kinetic data on the labeling index (LI), DNA synthesis time (ts), and potential doubling time (tpot) of epidermic cells in relation to sex, age, and site were obtained by in vitro incubation of skin cylinders from 45 human cadavers with DNA precursors 3H- and 14C-thymidine. In a first study on parts of the same material, it was established that LI over a period of more than 70 h and tpot over a period of at least 30 h remained essentially unchanged and are comparable with live humans, when the cadavers were stored at 4 degrees C. The following results were obtained: The female and male cadavers had a LI of 2.6% (+/- 0.8%) or 2.5% (+/- 0.8%), a ts of 3.9 h (+/- 0.2 h) or 5.0 h (+/- 1.6 h), and a tpot of 168.5 h (+/- 34.3 h) or 183.9 h (+/- 27.2 h). The LI for the thigh and knee ranged between 21.3% and 25.8% in different age groups. No statistically relevant differences were established between the sexes or among the age groups. Topographic allocation of the proliferative-kinetic data ultimately showed that, on the average, LI was relatively high at the elbow (3.1% +/- 1.0%) with short tpot (109.3 +/- 72.5 h) and a comparatively large epidermal diameter (47.1 microns); by contrast, LI at the lower abdomen was impressively low (2.1% +/- 0.8%), tpot relatively long (183.0 +/- 138.7 h) and mean epidermal diameter relatively small (23.0 microns). Nevertheless, no statistically relevant differences were established between data for elbow and lower abdomen or between other data for different sites. The proliferative-kinetic data for human cadavers were compared with data reported in the literature for live humans.

Fibronectin quantification in plasma and vitreous by a noncompetitive ELISA technique

Fibronectin, a high-molecular glycoprotein of the extracellular matrix and plasma, has provoked increasing interest in ophthalmology because of its possibly important role in the pathogenesis of proliferative vitreoretinopathy (PVR). A quantitative determination of fibronectin in vitreous aspirates is necessary for the evaluation of this glycoprotein in PVR. A noncompetitive enzyme-linked immunosorbent assay (ELISA) was developed for the quantification of immunoreactive fibronectin in human plasma samples and vitreous aspirates. Here, procedures to establish an ELISA for the clinical laboratory routine are discussed and possible pitfalls during the assay standardization are described.

Ramification patterns of vasoactive intestinal polypeptide (VIP)-cells in the rat primary visual cortex. An immunohistochemical study

Vasoactive intestinal polypeptide (VIP)-immunoreactive cells in the primary visual cortex of the rat were classified on the basis of ramification pattern of cell processes. The distribution of cells over cortical layers, and proportions of cell classes relative to total cell numbers were evaluated by means of quantitative methods. Two main types of VIP-positive neurons, the bipolar and the multipolar were distinguished constituting 76% and 24% of the VIP populations, respectively. The axons of vertically oriented bipolars were observed to ramify within a column around the descending dendrite. By contrast, multipolar cells have a non-oriented ramification pattern. The two overlapping axonal systems form the VIP-innervation of the rat visual cortex.

Types and spatial distribution of vasoactive intestinal polypeptide (VIP)-containing synapses in the rat visual cortex

In the rat visual cortex vasoactive intestinal polypeptide (VIP)-containing structures were studied by means of light and electron microscopy and image analysis. VIP-immunoreactive axon terminals were found to form symmetric synapses with small dendritic shafts, dendritic spines and somata of pyramidal cells and interneurons. VIP-terminals often occurred in pairs with VIP-negative, asymmetric synapses on the same postsynaptic structure. VIP-immunostained dendrites and perikarya were contacted by a purely asymmetric and a mixed population of VIP-negative terminals, respectively. Synaptic connections between two VIP-neurons are seldom as compared to the other types of VIP-synapses. Quantitative studies obtained by the image analysis of VIP-stained boutons and dendritic particles in light microscopic preparations suggest a distinct laminar distribution. Dendritic particles are most frequent in layers I-II, whereas axonal boutons have three laminar accumulations: at the border of layers I-II, in layer IV and layer VI. Together with previous results, the present findings argue for a non-random spatial distribution of VIP-boutons.

The significance of fibronectin in vitreoretinal pathology. A critical evaluation

Proliferative vitreoretinopathy (PVR) is characterized by cellular proliferation and the formation of intravitreal and periretinal membranes predisposing to traction retinal detachment. Recently, fibronectin, a high-molecular glycoprotein, has been attributed an important role in the pathogenesis of PVR. In order to evaluate the significance of fibronectin as a diagnostic order prognostic marker for PVR, we determined levels of immunoreactive fibronectin in 59 human vitreous specimens by a noncompetitive ELISA technique. Before this study, fibronectin levels in the vitreous had not been investigated taking both protein and iron levels into consideration. The vitreous was obtained during vitrectomies performed for a broad spectrum of vitreoretinal disorders. Our measurements suggest that the amount of intravitreal fibronectin may be correlated with the severity of a manifested disorder rather than being diagnostic for PVR. As long as plasma-derived fibronectin cannot be differentiated from other tissue fibronectins, however, the concentration of this glycoprotein is not a reliable indicator of intraocular proliferative activity. The values for all three parameters--fibronectin, protein, and iron--were significantly higher in revitrectomy samples compared to patients undergoing a first vitrectomy. A somewhat surprising result was a high level of fibronectin in the vitreous of two patients with macular pucker.

Local cerebral glucose utilization in the Ammon's horn and dentate gyrus of the rat brain

The local cerebral glucose utilization (LCGU) was measured in different regions and layers of the Ammon's horn and dentate gyrus in the conscious rat. The LCGU was determined by quantitative [14C]2-deoxyglucose autoradiography using a computerized image processing system. In the hippocampus, the various regions and layers exhibited different glucose consumptions, the lowest values being found in the alveus and the highest ones in the lacunosum-molecular layers of the sectors of the Ammon's horn and the molecular layer of the dentate gyrus' external limb. Additionally, in many layers, the LCGU values of the left hemispheres were found to be higher compared with the right hemispheres. The analysis of LCGU changes in rostrocaudal direction revealed, that in sector 1 of Ammon's horn and in the dentate gyrus the glucose consumption decreased from rostral to caudal levels, whereas in sector 3 of Ammon's horn an increase was found.

Quantitative receptor autoradiography in the human brain. Methodical aspects

Quantitative receptor autoradiography on sections of the human brain raises methodical problems of which some are relevant also for studies in animal tissue, but others are unique in studies of human brain tissue. Procedures for the following methodical aspects are discussed: image analysis for quantitation of the regional distribution of receptor densities, saturation analysis on autoradiographs, influence of age and post-mortem delay and quenching of beta-radiation in brain tissue. The solutions proposed to these problems make receptor autoradiography in the human brain to a reliable method for studies of chemical neuroanatomy.

Quantitative immunohistochemical analysis of VIP-neurons in the rat visual cortex

A critical appraisal of quantitative immunohistochemistry of neuropeptides is presented defining the main criteria of selecting the type of immune-staining and preparation suitable for these investigations. As an example of meeting the established criteria, the immunohistochemical demonstration of vasoactive intestinal polypeptide (VIP)-containing neurons in the rat brain and the processing of VIP-immunostained preparations for computer-controlled image analysis are described.

Effect of the 5-HT1A receptor agonist ipsapirone on the local cerebral glucose utilization of the rat hippocampus

Local cerebral glucose utilization (LCGU) was measured in the hippocampus of the rat brain following i.p. injection of the anxiolytic drug and 5-HT1A receptor agonist ipsapirone (TVX Q 7821). Administration of ipsapirone (5 mg/kg) reduced glucose utilization in the various hippocampal areas to variable extent. The most subtle reduction took place in the dorsal subiculum, while the most pronounced decrease was found in sector CA4 of Ammon's horn. The degree of LCGU reduction can be related to the 5-HT1A receptor density in the respective areas.

Comparative aspects of the primate posterior cingulate cortex

Cytoarchitecturally defined cortical areas of the posterior cingulate gyrus differ morphometrically among the major taxonomic divisions of primates. Prosimians and anthropoids have different laminar proportions in the isocortical regions (areas 30, 23, and 31); anthropoids have relatively larger outer main laminae and granular layers than prosimians. In the granular retrosplenial cortex (area 29), however, prosimians and anthropoids differ only in the proportion of the molecular layer to the rest of the cortex. On the other hand, the proportions of the inner and outer main laminae of area 29 differ between the infraorder divisions of Anthropoidea, the catarrhines, and the platyrrhines. The platyrrhines (New World monkeys) have apparently specialized by increasing the outer main lamina of area 29, which contains afferent and intracortical connections. Among all primates, the amount of neuropil in each cortical region changes as a function of brain weight, but within each area, the neuropil maintains a constant ratio between the outer and inner laminae. These observations suggest that neuropil ratios are conservative features in primates and that evolutionary changes more frequently involve shifts in volumetric proportions. Furthermore, the platyrrhine-catarrhine differences in area 29 likely evolved after the prosimian-anthropoid differences were established in the isocortical cingulate regions.

Quantitative cytoarchitectonics of the posterior cingulate cortex in primates

The cytoarchitecture of four cortical areas within the posterior cingulate region and the differences among them are quantitatively analyzed in 17 primate species. The transition from allocortex (area 29) to isocortex (areas 30, 23, and 31) is characterized by shifts in laminar proportions and cellular densities. The molecular layer and inner main lamina (layers V and VI) occupy a smaller proportion of the cortex in iso- than in allocortex, while conversely, the outer main lamina (layers II and III) makes up a larger proportion of the cortex in iso- than in allocortex. Layer IV is relatively larger in area 31 than in area 23. The packing densities of cell bodies were determined by gray-level index values. These values show that the isocortex has lower cell densities in the outer main lamina, but higher cell densities in the inner main layers. Furthermore, the granular layer of area 31 is more densely packed than it is in area 23. These results are discussed as structural correlates of a relative increase in the receptive and processing capacities of the isocortex over the adjacent allocortex.

Quantitative autoradiography of transmitter binding sites with an image analyzer

A computerized image processing system for quantitative receptor autoradiography on tritium-sensitive film is described. The method implements an image analyzer (IBAS 1 + 2) for the acquisition of an image which is evaluated with respect to the regional distribution of binding site densities by a small computer which is connected to a digitizer. Several methodological problems must be considered when using tritium-labelled compounds and an image analyzer. The use of tissue standards and shading procedures, the improvement of signal-to-noise ratio, the calibration of the system which establishes the non-linear relation between grey values and concentration of radioactivity, the contrast enhancement and the quenching problem are discussed. This method permits a quick and precise quantitative analysis of binding site distribution in receptor autoradiography.