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Biomedical subjects

L Werner

Publications and source records attributed to L Werner.

At least 127 records · Page 7Linked to original sources
PubMed1978

[Axon-like glial extensions in the pars ventralis of the corpus geniculatum laterale (CGLv) of the albino rat].

In sections of the Corpus geniculatum laterale, pars ventralis (CGLv) of adult albino rats impregnated according to Golgi-Kopsch, structures are visible very similar to long unbranched axons with large boutons en passage. Within the CGLv these axon-like structures can be followed parallel to the optic tract. Generally they take a ventro-dorsal, exceptionally a dorso-ventral course. As well in Golgi-Kopsch material as in sections in which glial cells are specifically impregnated the described structures could be traced to cells mainly located subpial in the Tractus opticus. Within the optic tract these axon-like structures change their appearance looking similar as the numerous other processes originating from these cells too. These other processes take a course right-angled to the optic fibers and in general they don't bear axon-like structures as described. In our opinion based also on investigations of Nissl-stained sections the origination cells represent a specialized type of astroglia of until now unknown function.

Afferent Pathways↗
PubMed1977

[Automatic pictorial analysis of normal and experimentally altered nervous tissue].

1. Structural changes of the dorsal LGN of the albino rat following unilateral enucleation cause its decrease of volume. 2. Using the Quantimet 720 M and Nissl stained preparations we tried to explain the decreased volume by estimation of three parameters: The whole area of the cells, the number of neurons and the size distribution of cells. 3. The whole area and the number of neurons are constant. 4. The size distribution of cells changes significantly and indicates an alteration of the tissue surrounding the cells (development of the neuropil, loss of fibers). 5. The changes of the maxima of size distributions following enucleation suggest a diminution of the area of neuron somata, but are not significant. 6. Using more exact methods of measurements we want to get more detailed results.

Animals↗
PubMed1976

[Studies on the spine density in lamina V pyramidal cells of the visual cortex in young and subadult rats after dark-rearing and destruction of the dorsal nucleus in the lateral geniculate body].

1. Dark reared 50 days old rats have a significantly diminuished number of spines at the apical dendrite of the lamina-V-pyramidal cells in the visual cortex. 2. Likewise we could ascertain a significant diminution of spines after destroying the upsilateral Cgld. The topistical distribution of spine density differs in both investigated series. 3. The spine diminution at the apical dendrites of lamina-V-pyramidal cells differs in this way: pyramidal cells with thick apical dendrites show a weaker spine diminution than the pyramidal cells with thin apical dendrites. 4. Some topistical problems concerning specific afferents in the visual cortex are discussed.

Age Factors↗
PubMed1976

[Studies on the structure of thalamo-cortical projection neurons and interneurons in the Corpus geniculatum laterale pars dorsalis of albino rats after different histological treatments].

1. In the dorsal part of the lateral geniculate body of the albino rat (Wistar strain) the identification of relay neurons and interneurons has been carried out and the findings in Golgi and Nissl preparations were compared with those in the semithinn sections and in the electron microscopic preparations. 2. The effect of different histolical treatments (perfused by Karnovsky's fluid and embedded in micropal; immersed or perfused by Bouin's fluid, formalin or glutaraldehyde and embedded in celloidine or paraffin) in the structure of the relay neurons and the interneurons in combination with the Nissl method is described. 3. Following immersion the cytoplasm of the relay neurons is relatively broad and has a rough structure in the extreme case (glutaraldehyde) it is vacuolized due to hypoxie or anoxie. In these preparations we could not extimate dark neurons. 4. Following perfusion the cytoplasm of the relay neurons has a fine structure and is more narrow than following fixation by immersion. Furthermore the cell nucleus is enlarged. 5. The identification of interneurons is possible to a high degree of security only after fixation with one of the both aldehydes according to the well-known criteria. When Bouin's fluid is applied the chromatin particle at the nucleolus as one of the important discriminators is not represented. 6. In the single groups the relay neurons were characterized by quantitative parameters. As statistical method of calculation the paired comparison is used. The findings about the semithinn sections are regarded as the standard values because this material is expected to give the most reliable equivalent picture. 7. In 9 out of 12 cases the diameter of the cell soma is smaller and in 3 cases larger than the standard value. 3 values (perfused by Bouin's fluid and embedded in paraffin; immersed by formalin and embedded in celloidine; immersed by glutaraldehyde and embedded in celloidine) do not present remarkable deviation from the standard value. 8. Amongst the diameters of the nuclei only one value is larger than the standard value. 7 values do not significantly differ from the standard value, among them the values of meterial perfused by Bouin's fluid and embedded in paraffin and also immersed by formalin and embedded in celloidine. 9. All the quotientes from soma diameter and nucleus diameter are significantly different to the standard value. The difference between the values of immersion by Bouin's fluid and the standard value is the smallest one. 10. Although the values of soma diameter and nucleus diameter of the mateiral following perfusion by Bouin's fluid and embedding in paraffin as well as following immersion by formalin and embedding incelloidine are not significantly different to the standard value, we prefer immersion by formalin and embedding in celloidine because it is the most suitable method solving the special problems concerning the identification of relay neurons and interneurons in Nissl preparations and the metrical comparisons with findings in Golgi investigations.

Animals↗
PubMed1975

[Qualitative and quantitative studies on the corpus geniculatum laterale (Cgl) of the laboratory rat. IV. Qualitative structure analysis of the pars dorsalis an on India-ink-injected Nissl preparation].

1. The histological organization of the rat dorsal lateral geniculate nucleus (Cgld) has been analysed in Nissl-preparations following vessel injection with india ink. 2. The findings have been collected by means of a non-automatically visual scanning method. Every point is defined by 3 coordinates. 3. Different parameters have been collected in every point: the number of the 5 structural elements of the nervous tissue (neurons, fragments of capillaries, nuclei of astrocytes, oligodendrocytes and microglia) and the hit points per structural element. 4. In addition the differentiation of about 15500 neurons in relay neurons and interneurons has been carried out. The ratio of the 2 types of neurons is about 14:1. 5. The collected values have been statistically analysed by correlation, regression and discriminatory analyses. 6. The results relate to the correlation between the structural elements and the rostrocaudal, lateromedial and ventrodorsal directions as well as the structural elements with another. 7. At 5 levels the Cgld has been mapped on the basis of neuron size, neuron density, capillary density, density of the 3 types of glial nuclei and the relative number of hit points per structural element. 8. In the Cgld we distinguish 2 portions regarding the neuron size. The mediocellular portion occupies the lateral, ventral and caudal parts and encloses a magnocellular portion like a coat. 9. The distribution pattern of the interneurons does not correlate with the size of neurons. 10. The capillaries tend to have a greater density in the lateral area of the Cgld. 11. The correlation and regression coefficientes and the distribution pattern of the astrocytes and oligodendrocytes suggest that both glial types show a reciproke ratio in the Cgld. 12. The distribution pattern of the microglia is relatively uniform. 13. Mapping the Cgld we have got a model conception of its structural condition corresponding with the common mammalian scheme. 14. By the discriminatory analysis zones of input and fields of projection have been discriminated. It was possible to discriminate the ipsi- and contralateral input zones, but not the binocular and monocular projection fields. 15. The discriminatory analysis allows to show the collective biological effect of all structural elements in a uniform mathematical value.

Animals↗
PubMed1975

[Relais cells and afferent axons in the dorsal part of the lateral geniculate body in the albino rat under geometrical aspects].

1. The average volumes of dendritic domaines of relay neurons (P-neurons) were calculated and the quantitative relations to the neuronal elements situated in this area were investigated. Likewise we carried out measurements and calculations at the terminal parts of afferent axons, to find a conception concerning possible contacts between axons and P-neurons considering quantitative aspects. 2. The dendrites of one P-neuron are distributed in an area of about 0,008 mum3. In this area there are located somata of at least 120 other P-neurons and dendrites of altogether about 900 P-neurons. 3. The type-1-axons (cortical afferents) run almost linearly in the longitudinal system of the CGLd. Traversing a distance adequate to the diameter of a P-neuron (250 mum) the dendrites of 150 to 170 P-neurons may cross the course of one axon. At this distance the axon, however, has just set up about 50 boutons, thus synaptic contacts may be established with one third at most of the existing cells. A type-1-axon that is bifurcating in the entrance area into the CGLd is altogether of about 2000 mum in length and is able to develop about 420 presynaptic profiles. 4. The type-2-axons (retinal afferents) show a distinct terminal branching zone. The Golgi-Kopsch impregnated terminals of type-2a-axons are distributed in a space of 147000 mum3 capacity, the corresponding terminals of type-2b-axons in a space of 443000 mum3. The type-2a-axons having an average number of 23 boutons, may contact the dendritic branching zones of 25 P-neurons. There is a good reason to assume that type-2b-axons are in contact also with terminal dendritic parts of P-neurons. Thus the number of P-cells, which spread their dendrites into the terminal branching zone of one type-2b-axon may amount to 540. The average number of boutons of one type-2b-terminal, however, is only about 160. This means that synaptic contacts may be developed to the P-neurons-dendrites not exceeding 30% of them. 5. Various aspects of divergence of axon terminals in the albino rat's CGLd are discussed.

Animals↗