Untersuchungen an den Nervi optici und an den Gehirnen von Schafen mit Mikrophthalmie

Inhalt An 6 Schafen mit angeborener Mikrophthalmie wurden morphologische und histologische Untersuchungen am Gehirn und an den Groβhirnhemisphären durchgeführt und die Befunde mit denen bei 3 Kontrolltieren verglichen. Das Gehirngewicht und die Länge der Hemisphären sind etwas kleiner als bei den entsprechend altersgleichen Kontrollgehirnen. Zwei Probanden weisen eine leichte Umfangsverminderung im Bereich der okzipitalen Kortex auf. Die Zytoarchitektonik der Area striata weist eine stärkere Variation auf, als bei den Kontrollgehirnen; grundsätzlich entspricht sie jedoch dem Rindenmuster normal entwickelter Schafe. Die zytologischen Veränderungen treten in der visuellen Kortex – wie auch im Colliculus anterior, jedoch im Gegensatz zum Corpus geniculatum laterale – hauptsächlich an den kleinen und kleinsten Nervenzellen auf. Die für die postnatale Entwicklung charakteristische Nivellierung der Zelldichte zu einer gleichmäβigen Zellverteilung ist vermindert. Der Gehalt an Markfasern, die in die visuelle Kortex ziehen, ist herabgesetzt. Contents Investigations on the optic nerves and brains of microphthalmic sheep. Communication III: Report of the brain and the cortical hemispheres. Morphological and histological experiments on the brain and the cortical hemispheres were carried out on 6 sheep with congenital microphthalmia. Theresults were compared with 3 control animals. The weight of the brains and the length of the hemispheres were somewhat less in the experimental animals of the same age. In 2 of the experimental animals, the circumference of the occipital cortex was slightly less. The cytoarchitectonics of the area striata showed more variation in the experimental animals. In other respects, however, the cortex resembled that of normal sheep. The cytological differences occured in the visual cortex as well as in the colliculus anterior. In contrast to the corpus geniculatum laterale, the variations generally appeared in the small and smallest nerve cells. The uniform distribution of cells, a process which takes place during postnatal development, was diminished. The number of myelinated fibers which extend through the visual cortex was decreased.     

Characterization of some Middle European soil textures by gamma‐spectrometry

Information about the variability of different soil attributes within a field is essential for sustainable land management and precision agriculture. Mobile proximal gamma‐ray spectrometry can map soil characteristics of vast areas at different scales rapidly and cost‐effectively. This study aims at investigating reliability and capability of mobile‐gamma‐spectrometry (radiometrics) data to map typical soils of Middle Europe. In this paper, we investigate relationships between the radioelement concentrations (K, U, Th, and dose rate) and soil parameters (texture, CEC, pH, and organic‐C content) at four different field sites and soil textures. The data reliability is confirmed at the survey start. Mobile data have an excellent linear correlation (nearly 1:1) with the stationary readings (of identical devices, acquisition setups, and soil conditions) but moderate correlation with laboratory data (of different devices, setups, and sample conditions). Dried lab samples have systematically higher radioelement concentrations than the field soils (normally wet). Consequently, the mobile‐gamma‐spectrometric data is sufficiently accurate for soil mapping, and its calibration by laboratory data is less useful due to the varying environmental conditions. Single absolute radioelement concentrations show only moderate correlations with the different soil parameters, particularly clay content and CEC. This may be related to varying environmental conditions (soil moisture, soil structure, vegetation, land use, etc.) between the study sites. Investigations of the ratios of radioelement concentrations yield a clear improvement of their correlations to soil parameters, especially for sand and clay contents, CEC, and organic C. Additionally, multiple‐linear‐regression models were established using the element concentrations of potassium and thorium to predict silt content and pH. The results of the highly correlated models were confirmed by comparing with clay and silt content and pH value, respectively, to six additional independent field samples. Briefly, applications of gamma‐ray data for soil mapping offers the possibility of the development of quantitative relationships regarding soil parameters like sand and clay contents, CEC, and organic C. Classification of soil textures by gamma‐ray data seems to be promising, though a broader database of soils is needed for further research. We recommend gamma‐ray mapping as a complementary or even an alternative to common mapping techniques.