Histology and histopathology Vol. 7, nº 4 (1992)
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- PublicationOpen AccessUltrastructural study of neuromuscular junction in rectus femoris muscle of streptozotocin-diabetic rats(Murcia : F. Hernández, 1992) Medina sánchez, M.; Rodríguez Sáchez, C.; Vega Alvarez, J.A.; Menéndez Peláez, A.The neuromuscular junctions (NMJ) from rectus femoris muscle in streptozotocin (STZ) -induced diabetic rats were examined by electron microscopy eight weeks after the STZ injection. When compared to controls and vehicle-injected groups, both the axon terminal and the junctional sarcoplasm showed serious alterations including mitochondrial degeneration, presence of myeloid bodies, breakdown of presynaptic membrane and changes in the form of the synaptic vesicles. The results suggest that NMJ can contribute to the pathogenesis of diabetic proximal myopathy.
- PublicationOpen AccessLesion and regeneration in the medical cerebral cortex of lizards(Murcia : F. Hernández, 1992) López-García, Carlos; Molowny, A.; Martínez Guijarro, F.J.; Blasco-lbáñez, J.M.; Luis de la Iglesia, J.A.; Bernabeu, A.; García-Verdugo, J.M.The cerebral cortex of Squamate reptiles (lizards and snakes) may be regarded as an archicortex or ereptilian hippocampus». In lizards, one cortical area, the media1 cortex, may be considered as a true ~fascia dentata» on grounds of its anatomy, connectivity and cyto- chemo-architectonics of its main zinc-rich axonal projection. Moreover, its late ontogenesis and postnatal development support this view. In normal conditions, it shows delayed postnatal neurogenesis and growth during the lizard's life span. Remnant neuroblasts in the media1 cortical ependyma of adult lizards seasonally proliferate. The late-produced immature neurocytes migrate to the medial cortex cell layer where they differentiate and give off zinc-containing axons directed to the rest of cortical areas. This results in a continuous growth of the medial cortex and its zinc-rich axonal projection. Perhaps the most important characteristic of the lizard medial cortex is that it can regenerate after having been almost completely destroyed. Recent experiments in our laboratory have shown that chemical lesion of its neurons (up to 95%) results in a cascade of events; first, those related with massive neuronal death and axonal-dendritic retraction and, secondly, those related with a triggered neuroblast proliferation and subsequent neohistogenesis, and the regeneration of an almost new medial cortex that shows itself undistinguishable from a normal undamaged one. This is the only report to our knowledge that an arnniote central nervous centre may regenerate by new neuron production and neo-histogenesis. Perhaps the media1 cortex of lizards may be used as a model for neuronal regeneration andlor transplant experiments in mammals or even in primates.
- PublicationOpen AccessInfluence of preoperative dexamethasone therapy on proliferating cell nuclear antigen (PCNA) expression in comparison to other parameters in meningiomas(Murcia : F. Hernández, 1992) Gottschalk, J.; Goebel, S.; Jautzke, G.; Martín, H.; Zimmer, C.; Marzheuser-Brands, S.; Cervós-Navarro, J.We conducted a trial in 42 benign and malignant meningiomas to assess a possible influence of preoperative dexamethasone therapy on mitotic index, labelling indices of proliferating cell nuclear antigen (PCNA), progesterone receptor, epidermal growth factor receptor (EGF-R), c-erbB-2 oncoprotein, cathepsin D, gamma-gamma enolase as well as the mean number of silver-stained nucleolar organizer region-associated proteins (AgNORs). Tumors with preceding dexamethasone therapy for more than 1 day display significantly less immunohistochemical staining for PCNA. A correlation between the labelling index of PCNA and the degree of malignancy could not be identified. There was no significant effect of preoperative dexamethasone therapy on the other parameters. Our data suggest that dexarnethasone may selectively inhibit the expression of PCNA in the GlISphase of the cell cycle. Thus, we emphasize the necessity to heed factors, e.g. dexamethasone, which may affect the expression of proliferating markers.
- PublicationOpen AccessStereological study of the synaptic profiles belonging to interneurons in the dorsal lateral geniculate nucleus of the rabbit(Murcia : F. Hernández, 1992) Carmona Martos, R.; Abadía Molina, F.; Luján Miras, R.; Calvente Iglesias, R.; Abadía Fenoll, F.-
- PublicationOpen AccessCircadian and seasonal cortico-medullary variations in pinealocyte nuclear size. A comparative statistical analysis(Murcia : F. Hernández, 1992) Cimas García, C.; Martínez Soriano, F.; Ruíz Torner, A.Circadian and seasonal variations were observed in the karyometric index of pinealocytes in the cortical and medullary regions of the dista1 pineal body. The study involved 70 Wistar rats over a 24-hour interval(0:6, 10:00, 14:00, 18:00, 22:00,02:00,06:00 h) during two natural photoluminous periods, i.e. late summer (Long photoperiod) and Winter (Short photoperiod). The results show a difference between the high and low points of both photoperiods. Corticomedullary differences are found at different times of day during long photoperiod (0:6; 10:OO; 14:00 and 18:OO h.) and short photoperiod (14:OO; 22:OO and 02:OO h.). The varianza annalysse between nuclear volume and pointtime and between nuclear volume, point-time and location are significative. A high correlation between circadian rhythms and volumetric variations in both layers and photoperiod are found. The results also show significant differences in cortico-medullary karyometric indices between both seasons as well as between the diurna1 and nocturna1 hours of both photoperiods. It is suggested that the pineal body of the rat is influenced by circadian and seasonal photoperiod and may have groups of cells with different functional characteristics, depending on their location within the gland