The Ependyma of the Cat Central Canal, with Particular Reference to its Mitochondria-Containing Bulbs

The ultrastructure of the ependyma in the central canal of adult cats was examined in both the scanning and the transmission electron microscopes (SEM and TEM). The same morphological details were seen in the ependyma of the central canal as have so frequently been described in the ependyma of the brain ventricular system, for example bundles of cilia, single cilia, microvilli and occasional small cytoplasmic protrusions. The supraependymal cells and supraependymal nerve fibers found in the central canal also resembled those seen in the ventricular system. The most striking feature of the canal ependyma were the large, spherical bodies containing numerous mitochondria. They are therefore called mitochondria-containing bulbs. In sections the bulbs were seen to be connected by long, slender stalks to neurons in subependymal position. In some respects the mitochondria-containing bulbs resemble the processes of cerebrospinal fluid-contacting neurons

Frauenforschung in der Soziologie - quo vadis?

It is widely accepted that the devastating consequences of spinal cord injury are due to the failure of lesioned CNS axons to regenerate. The current study of the spontaneous tissue repair processes following dorsal hemisection of the adult rat spinal cord demonstrates a phase of rapid and substantial nerve fibre in‐growth into the lesion that was derived largely from both rostral and caudal spinal tissues. The response was characterized by increasing numbers of axons traversing the clearly defined interface between the lesion and the adjacent intact spinal cord, beginning by 5 days post operation (p.o.). Having penetrated the lesion, axons became associated with a framework of NGFr‐positive non‐neuronal cells (Schwann cells and leptomeningeal cells). Surprisingly few of these axons were derived from CGRP‐ or SP‐immunoreactive dorsal root ganglion neurons. At the longest survival time (56 days p.o.), there was a marked shift in the overall orientation of fibres from a largely rostro‐caudal to a dorso‐ventral axis. Attempts to identify which recognition molecules may be important for these re‐organizational processes during attempted tissue repair demonstrated the widespread and intense expression of the cell adhesion molecules (CAM) L1 and N‐CAM. Double immunofluorescence suggested that both Schwann cells and leptomeningeal cells contributed to the pattern of CAM expression associated with the cellular framework within the lesion

Polysialylated-neural cell adhesion molecule (PSA-NCAM) in the human trigeminal ganglion and brainstem at prenatal and adult ages

<p>Abstract</p> <p>Background</p> <p>The polysialylated neuronal cell adhesion molecule (PSA-NCAM) is considered a marker of developing and migrating neurons and of synaptogenesis in the immature vertebrate nervous system. However, it persists in the mature normal brain in some regions which retain a capability for morphofunctional reorganization throughout life. With the aim of providing information relevant to the potential for dynamic changes of specific neuronal populations in man, this study analyses the immunohistochemical occurrence of PSA-NCAM in the human trigeminal ganglion (TG) and brainstem neuronal populations at prenatal and adult age.</p> <p>Results</p> <p>Western blot analysis in human and rat hippocampus supports the specificity of the anti-PSA-NCAM antibody and the immunodetectability of the molecule in postmortem tissue. Immunohistochemical staining for PSA-NCAM occurs in TG and several brainstem regions during prenatal life and in adulthood. As a general rule, it appears as a surface staining suggestive of membrane labelling on neuronal perikarya and proximal processes, and as filamentous and dot-like elements in the neuropil. In the TG, PSA-NCAM is localized to neuronal perikarya, nerve fibres, pericellular networks, and satellite and Schwann cells; further, cytoplasmic perikaryal staining and positive pericellular fibre networks are detectable with higher frequency in adult than in newborn tissue. In the adult tissue, positive neurons are mostly small- and medium-sized, and amount to about 6% of the total ganglionic population. In the brainstem, PSA-NCAM is mainly distributed at the level of the medulla oblongata and pons and appears scarce in the mesencephalon. Immunoreactivity also occurs in discretely localized glial structures. At all ages examined, PSA-NCAM occurs in the spinal trigeminal nucleus, solitary nuclear complex, vestibular and cochlear nuclei, reticular formation nuclei, and most of the precerebellar nuclei. In specimens of different age, the distribution pattern remains fairly steady, whereas the density of immunoreactive structures and the staining intensity may change and are usually higher in newborn than in adult specimens.</p> <p>Conclusion</p> <p>The results obtained show that, in man, the expression of PSA-NCAM in selective populations of central and peripheral neurons occurs not only during prenatal life, but also in adulthood. They support the concept of an involvement of this molecule in the structural and functional neural plasticity throughout life. In particular, the localization of PSA-NCAM in TG primary sensory neurons likely to be involved in the transmission of protopathic stimuli suggests the possible participation of this molecule in the processing of the relevant sensory neurotransmission.</p

El uso de estrategias de afrontamiento y habilidades metacognitivas ante situaciones de bullying y cyberbullying

Bullying y cyberbullying son fenómenos que están recibiendo en los últimos tiempos una gran atención debido a su alta presencia en los centros educativos. Entre las variables que ayudan a reducir el problema y su impacto están las estrategias de afrontamiento, cuyo uso se encuentra asociado a variables personales y contextuales. En este estudio, se ha querido analizar el peso que tienen los procesos metacognitivos, fundamentales en la autorregulación de la conducta, en el uso de las estrategias de afrontamiento que se ponen en marcha ante los problemas de bullying y cyberbullying. Para ello se ha evaluado a 346 sujetos con edades comprendidas entre 12-18 años que se encuentran estudiando la Educación Secundaria Obligatoria (49%?; Edad M=14.05; DT=1.37) mediante un método selectivo de encuestas aplicándose los cuestionarios ECIPQ, EBIPQ, Brief-Cope y un Inventario de Habilidades Metacognitivas. Los resultados nos indican que cuando los sujetos llevan a cabo actuaciones que denotan el uso de habilidades metacognitivas adecuadas o de calidad aumenta el empleo de las estrategias de afrontamiento, en especial de planificación. El uso de los procesos metacognitivos también varió de acuerdo a la frecuencia de participación en episodios de bullying. Se discuten posibles explicaciones