Map plasticity in somatosensory cortex

Sensory maps in neocortex are adaptively altered to reflect recent experience and learning. In somatosensory cortex, distinct patterns of sensory use or disuse elicit multiple, functionally distinct forms of map plasticity. Diverse approaches-genetics, synaptic and in vivo physiology, optical imaging, and ultrastructural analysis-suggest a distributed model in which plasticity occurs at multiple sites in the cortical circuit with multiple cellular/synaptic mechanisms and multiple likely learning rules for plasticity. This view contrasts with the classical model in which the map plasticity reflects a single Hebbian process acting at a small set of cortical synapses.     

Synaptic changes in layer 2/3 underlying map plasticity of developing barrel cortex

The functional and anatomical rearrangements of cortical sensory maps accompanying changes in experience are not well understood. We examined in vivo and in vitro how the sensory map and underlying synaptic connectivity of the developing rat barrel cortex are altered when the sensory input to the cortex is partially deprived. In the nondeprived cortex, both the sensory responses and synaptic connectivity between columns were strengthened through an increase in the synaptic connection probability between L2/3 pyramids in adjacent columns. This was accompanied by a selective growth of L2/3pyramid axonal arbors between spared columns. In contrast, deprived and nondeprived cortical columns became weakly connected in their L2/3 pyramid connections.     

Quantification,Morphology and Ultrastructure of Preantral Follicles of Buffalo (Bubalus bubalis) Foetuses

The objective of this study was to determine the number, morphology and ultrastructure of preantral ovarian follicles of buffalo (Bubalus bubalis) foetuses at different ages. Quantification revealed number of primordial, primary and secondary follicles of 48 857 ± 17 506, 26 000 ± 20 452, 18 428 ± 10 875 and 18 375 ± 19 690, 225 ± 349, 326 ± 288 at 12–34 cm and 35–60 cm crown rump length (CRL), respectively. Follicular diameter values were 28.9 (±3.4), 34.7 (±5.9) and 59.4 (±12.6) μm; oocyte diameters were 21.7 (±2.8), 24.3 (±3.4) and 33.0 (±7.7) μm, and the numbers of follicular cells in the follicle equatorial section were 7.1 (±1.4), 12.0 (±2.4) and 13.8 (±2.4) for primordial, primary and secondary follicles, respectively. The primordial follicle consisted of an oocyte surrounded by a layer of flattened follicular cells with a normally eccentric oocyte nucleus. Dispersed Golgi complex, smooth endoplasmic reticulum, rounded mitochondria and several lipid vesicles were observed in the cytoplasm and cell junctions between the follicle cell membranes and the oocyte. This work describes the number, morphometry and ultrastructure of preantral follicles of buffalo foetuses, concluding that folliculogenesis is established between 8 and 34 cm CRL and that follicle number varies individually and according to age and that further studies are needed in this species.     

Die Chloroplasten-Thylakoid-Membran: Biogenese,Pigmentorganisation, Protein-Funktionsbeziehungen und Degeneration während der Seneszenz. Eine Übersicht

Zusammenfassung Chloroplasten enthalten charakteristische Membranstrukturen, die als Thylakoidmembranen bezeichnet werden, die im Energiestoffwechsel der grünen Pflanzen die Funktion der Energieabsorber für das Sonnenlicht erfüllen und gleichzeitig die absorbierte S rahlungsenergie in für biochemische Reaktionen verwertbare Energie- und Reduktionsäquivalente umwandeln.Gegenstand der vorliegenden Übersicht sind einige Aspekte der Thylakoidforschung, so die Biogenese der Membranen, Struktur und Funktion der Proteinkomponenten, die Organisation photosynthetischer Pigmente und der Abbau der Thylakoidmembranen im Verlauf der Seneszenz der Chloroplasten.

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The chloroplast thylakoid membrane: Biogenesis, organization of pigments, protein-function relationships and degradation during senescence — a review

Summary Chloroplasts contain specific membrane structures, so-called thylakoid membranes, which absorb the radiant energy of sunlight in green plants and convert the absorbed light energy into chemical energy forms available for the biochemical reactions of plant metabolism.In this paper some aspects of thylakoid research are discussed in form of a review, comprising the biogenesis of thylakoid membranes, the structure-function relations of protein components, the organization of photosynthetic active pigments in the membranes, and the degradation of thylakoid membranes during senescence of chloroplasts.

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