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Biomedical subjects

A Wree

Publications and source records attributed to A Wree.

47 records · Page 3Linked to original sources
PubMed1986

The size of the zone of origin of callosal afferents projecting to the primary visual cortex contralateral to the remaining eye in rats monocularly enucleated at different postnatal ages.

The cortical zone from which callosal afferents projecting to the primary visual cortex (area Oc1) originate was studied in monocularly enucleated and normal rats. The extent of this cortical strip was determined by retrograde labeling with HRP and by measurement of its width in coronal sections. Albino rats were monocularly enucleated from the 23rd ontogenetic day to the 120th and iontophoretical injections into Oc1 contralateral to the remaining eye were done more than one year after enucleation. The width of the labeled strip of perikarya in the hemisphere ipsilateral to the remaining eye was largest in neonatally enucleated rats (about 1.1 mm) and declined with increasing age at which enucleation was performed. Additionally, the perikarya of callosal afferents in the hemisphere ipsilateral to the remaining eye in rats enucleated as young adults (90th and 120th ontogenetic day) were labeled in significantly wider strips (about 0.6 mm) than in unoperated control rats (about 0.4 mm).

Afferent Pathways↗
PubMed1986

A quantitative approach to cytoarchitectonics: software and hardware aspects of a system for the evaluation and analysis of structural inhomogeneities in nervous tissue.

Cytoarchitectonic studies are based on the analysis of structural inhomogeneities in nervous tissue. Boundaries of brain regions are established where local structural properties such as numerical cell density, size, shape or orientation change. The measurement of these properties from histological sections with automatic devices is biased due to the thickness of the sections. In this study, the grey level index (GLI) is measured with a TV-based image analyzer from routine histological sections. This parameter is a biased estimate of the volume density of Nissl-positive structures. The histological section is digitized into GLI values by a computer-controlled scanning procedure. The result is stored in an image matrix which is processed by digital filtering in order to visualize the laminar pattern. GLI statistics of brain regions are evaluated from the pictorial data by delineating these regions with a cursor on a hard copy fixed to digitizer. Information from a series of sections is stored in a standardized data file and combined by specific application programs.

Animals↗
PubMed1985

Modification of callosal afferents of the primary visual cortex ipsilateral to the remaining eye in rats monocularly enucleated at different stages of ontogeny.

Callosal afferents to the primary visual cortex (area Oc1) mainly originate in the border region between the lateral portion of the primary visual cortex (area Oc1) and the laterally positioned secondary visual cortex (area Oc2L) of the contralateral hemisphere. The extent of this region has been determined by retrograde labeling with horseradish peroxidase (HRP). In normal rats the width of the retrogradely labeled cortical strip is about 0.3 mm. In rats monocularly enucleated from the 23rd up to the 44th ontogenetic day and subsequently injected as adults with HRP into Oc1 ipsilateral to the remaining eye, the perikarya of the callosal afferents from the opposite hemisphere are labeled in the form of significantly wider columns (about 0.8 mm) than in animals enucleated from the 50th ontogenetic day onwards. The latter do not differ from controls.

Afferent Pathways↗
PubMed1984

The monocular and binocular subfields of the rat's primary visual cortex: a quantitative morphological approach.

Primary visual cortex in the rat was studied by a variety of methods: transsynaptic transport of labelled amino acids, 2-deoxyglucose, and staining for perikarya, myelin, and acetylcholinesterase. The analysis was aided by a computer-controlled television image analyzer. The results obtained with different methods agree with one another in describing the position and extent of the entire primary visual cortex as well as its monocular (medial) and binocular (lateral) subareas.

Acetylcholinesterase↗
PubMed1983

A quantitative approach to cytoarchitectonics. VIII. The areal pattern of the cortex of the albino mouse.

The cerebral cortex of the albino mouse was examined by means of a quantitative method. An image analyzer was used in conjunction with an automatic scanning procedure to determine the grey level index in Nissl-stained sections. Computer plots of various ranges of grey level indices enabled delineation of cortical areas, from which cortical maps were graphically reconstructed. The cortical areal pattern is, in some regions, similar to the commonly used map of Caviness (1975) but differs considerably in other regions, especially in the temporal one. Furthermore, the primary visual cortex of the mouse was shown to be composed of two distinct cytoarchitectonic areas. The results of the study are discussed with respect to the literature on anatomical and functional localizations in the mouse cerebral cortex.

Animals↗
PubMed1983

[Compression of the radial nerve by a coracobrachial muscle. An anatomical study].

Whilst dissecting the body of a 76 year old male we observe an accessory muscle originating from the coracoid processus and inserting in the tendinous part of the latissimus dorsal muscle. The muscle crosses the radial nerve in the axilla, thus causing a strong narrowing of the nerve. The possibility of a resulting compression syndrome is discussed.

Aged↗
PubMed1982

Estimation of volume fractions in nervous tissue with an image analyzer.

The calculation of volume fractions in nervous tissue is a method often used in neuroanatomy. In ontogenetic studies and problems concerning aging, as well as after experimental procedures, volume fractions are calculated in order to quantify the results. Grey level index (GLI) and grey cell coefficient (GCC) are different parameters correlated to the volume density of cellular elements in nervous tissue. The grey cell coefficient (GCC) is defined as the volume fraction of cellular elements in a griseum (grey matter area) and is estimated by a basic stereological method (point counting) from observations in two dimensions. The grey level index (GLI), measured with an automatic image analyzer, is the areal proportion of projected profiles of all stained elements within a volume given by the area of the measuring field and the thickness of section. GLI and GCC are compared in specimens obtained by a special histological procedure, and a method to estimate volume fractions by means of GLI-measurement is described.

Animals↗
PubMed1981

Growth of fresh volumes and spontaneous cell death in the nuclei habenulae of albino rats during ontogenesis.

The growth of the nuclei habenulae medialis et lateralis of albino rats is described by monotonically increasing growth curves of fresh volumes during ontogenesis. The nucleus habenulae medialis matures earlier than the nucleus habenulae lateralis in the perinatal period. However, the two nuclei reach their final volume at about the same time. Simultaneous electron microscopic investigation reveals the phenomenon of spontaneous nerve cell degeneration within the nuclei habenulae during ontogenesis in spite of the non-overshooting growth curves for the habenular nuclei.

Animals↗
PubMed1981

A quantitative approach to cytoarchitectonics. VII. The areal pattern of the cortex of the Guinea pig.

The cerebral cortex of the guinea pig has been examined by means of a quantitative cytoarchitectonic method (Schleicher et al. 1978; Zilles et al. 1978a). In this method, a computer-controlled automatic image analyzer determines the grey level index of microscopic fields measuring 50 X 50 mu m in Nissl-stained sections by a systematic scanning procedure. Computer plots of serially sectioned histological slides from three hemispheres were produced by printing selected ranges of grey level indices. The delineation of cortical areas was worked out in these plots based on quantitative criteria. Cortical maps of the areal pattern were reconstructed graphically. The resulting cortical map of the guinea pig differs from that of Rose (1912), but it corresponds to the results of Friede (1960) and is in agreement with neurophysiological studies. In general, the areal pattern of the guinea pig is similar to that of the rat (Zilles et al. 1980), but there are also some differences. These differences are discussed with respect to functional considerations.

Animals↗
PubMed1980

Biomathematical analysis of the neuronal loss in the aging human brain of both sexes, demonstrated in pigment preparations of the pars cerebellaris loci coerulei.

The pars cerebellaris loci coerulei is a flat accumulation of perikarya representing a subnucleus of the locus coeruleus in the roof of the fourth ventricle of the brain in man. A quantitative study was done on this subnucleus; it comprised 67 specimens from individuals between 11 and 90 years. Nerve cell counts were performed on cleared mounted block preparations. Mathematical analysis of the data was performed using logistic growth functions. The results showed that with advancing age there is a loss of neurons in both sexes. This begins in the female approximately after age 40; in the male already at age 20 (reaching a lower value in old age). The final loss of neurons is more pronounced in the male than in the female. Male and female specimens did not differ in the total number of neurons. In both sexes the left side of the pars cerebellaris loci coerulei contained more neurons than the right.

Adolescent↗