Browsing by Subject "Postnatal development"

Now showing 1 - 5 of 5
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    No loss of melanopsin-expressing ganglion cells detected during postnatal development of the mouse retina
    (Murcia : F. Hernández, 2010) González-Menéndez, Irene; Contreras, Felipe; Cernuda-Cernuda, R.; García-Fernández, J.M.
    Melanopsin, an opsin protein expressed in mammalian retinal ganglion cells (RGCs), makes them responsive to light. Such photosensitive RGCs form the retinohypothalamic tract (RHT) that provides signals to the suprachiasmatic nucleus (SCN), the master regulator of circadian rhythms. The SCN is adjusted daily to the environmental day/night cycle by signal inputs incoming from the RHT. In the present work we have studied, using immunohistochemistry techniques, the types and number of cells which expressed melanopsin during the postnatal development of pigmented C3H/He mice maintained in a standard daily cycle (12-h light / 12-h dark). Our results clearly show for the first time that the retina maintains a rather constant number of melanopsinexpressing RGCs from the first postnatal day and, thus, demonstrate that no loss of these photosensitive cells occurs during postnatal development. This supports the general idea that the non-image-forming system, in which these cells are involved, is functional at the very early postnatal stage.
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    Postnatal development of dendritic reticulum cells and their immune complex trapping ability.
    (Murcia : F. Hernández, 1986) Yukata Imai; Michi Dobashi; Kazuo Terashima
    The postnatal development of dendritic reticulum cells in the rat popliteal lymph nodes was electron microscopically investigated in relation to the appearance of immune complex trapping capacity. The popliteal lymph nodes of neonatal rat consisted of loosely arranged fibroblastic reticulum cells. In the following stage, the ueripheral cortex and paracortex became distinguishable. The former was made up of an accumulation of small lymphocytes, scattered within a framework of reticulum cells. On te 28 th day, the first primary follicle appeared in the peripheral cortex. Simultaneously the immune complex could be trapped on the cytoplasmic membrane of reticulum cells, which were located in the central portion of the primary follicles. The early image of germina1 centers appeared corresponding to immune complex trapping areas. In the well-developed secondary follicles, the immune complex trapping cells were mainly localized in the cap area. Their cytoplasmic membranes formed the dendritic processes, on which the distinct ability of trapping of the immune complex was recognized. It was dernonstrated that the fibroblastic reticulum cells, forming the stromaof lymph nodes, were transformed into the typicai dendritic reticulum cells with labyrinth structures in the cap area. Desmosomal junctions were often found, not only between the dendritic reticulum cells themselves, but aiso between the dendritic reticulum cells and lymphocytes. We suggest that the desmosomal junctions play a role as the channel for a transmission of immunological information.
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    Scanning electron microscopy of capsaicin-pretreated trachea in the rat during postnatal developrnent
    (Murcia : F. Hernández, 1995) Yu, S. M.; Lin, K. H.
    The morphological changes of the tracheal surface were studied in neonatally capsaicin-pretreated rats by scanning electron microscopy. One week after neonatal capsaicin treatment, a sparse number of ciliated cells were dispersed among the microvilli-covered goblet cells similar to those of the sham-operated rats. Potential ciliated cells (progenitor cells) possessed a few long cilia and many short cilia. The ciliated cells possessed cilia with a smooth surface and a blunt end similar to that of the sham-operated rats. Two weeks after neonatal capsaicin treatment, numerous ciliated cells frequently in clusters were located among large patches of microvilli-covered goblet cells similar to those of sham-operated rats. Furthermore, the blunt ends of cilia and microvilli contained short star-shaped protrusions extending into the lumen of the trachea. One month after neonatal capsaicin treatment, the star-shaped protrusions became longer, and more irregular than those of sham-operated rats. The short cilia of the potential ciliated cells (progenitor cells) also became blunt and irregular in shape. The star-shaped protrusions of the microvilli of the goblet cells became larger and thicker than those observed at two weeks following capsaicinpretreatment. Two months after neonatal capsaicin treatment, the tracheal surface was lined with a much greater population of the ciliated cells than that at one month. A striking characteristic at this age was that globular mucin-containing secretory products were trapped within the cilia of the ciliated cells. The results of this study suggest that mucus secretion is probably blocked by the capsaicin-pretreatment. Furthermore, the star-shaped protrusions of cilia and microvilli may indicate that the mucociliary clearance mechanism is interfered with by the capsaicin-pretreatment.
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    Scanning electron microscopy of capsaicin-pretreated trachea in the rat during postnatal developrnent
    (Murcia : F. Hernández, 1995) Yu, S. M.; Lin, K. H.
    The morphological changes of the tracheal surface were studied in neonatally capsaicin-pretreated rats by scanning electron microscopy. One week after neonatal capsaicin treatment, a sparse number of ciliated cells were dispersed among the microvilli-covered goblet cells similar to those of the sham-operated rats. Potential ciliated cells (progenitor cells) possessed a few long cilia and many short cilia. The ciliated cells possessed cilia with a smooth surface and a blunt end similar to that of the sham-operated rats. Two weeks after neonatal capsaicin treatment, numerous ciliated cells frequently in clusters were located among large patches of microvilli-covered goblet cells similar to those of sham-operated rats. Furthermore, the blunt ends of cilia and microvilli contained short star-shaped protrusions extending into the lumen of the trachea. One month after neonatal capsaicin treatment, the star-shaped protrusions became longer, and more irregular than those of sham-operated rats. The short cilia of the potential ciliated cells (progenitor cells) also became blunt and irregular in shape. The star-shaped protrusions of the microvilli of the goblet cells became larger and thicker than those observed at two weeks following capsaicinpretreatment. Two months after neonatal capsaicin treatment, the tracheal surface was lined with a much greater population of the ciliated cells than that at one month. A striking characteristic at this age was that globular mucin-containing secretory products were trapped within the cilia of the ciliated cells. The results of this study suggest that mucus secretion is probably blocked by the capsaicin-pretreatment. Furthermore, the star-shaped protrusions of cilia and microvilli may indicate that the mucociliary clearance mechanism is interfered with by the capsaicin-pretreatment.
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    The potential adverse effect of 2.45 GHz microwave radiation on the testes of prenatally exposed peripubertal male rats
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2022) Andrašková, Sandra; Holovská, Katarína; Ševčíková, Zuzana; Andrejčáková, Zuzana; Tóth, Štefan; Martončíková, Marcela; Račeková, Enikö; Almášiová, Viera
    In utero development of organs is easily influenced by many environmental factors. The aim of this study was to elucidate the effect of microwave radiation (MR) at a frequency of 2.45 GHz and a specific absorption rate of 1.73 W/kg on intrauterine development of testis. Pregnant albino rats were exposed to whole-body MR for 2 hours per day throughout the pregnancy. Male offspring (n=12, age 35 days) were not exposed to MR after birth. The study revealed that MR applied in utero induced apparent structural changes in the testes, such as irregular shape of seminiferous tubules, significant decrease in the diameter of seminiferous tubules (p<0.05) and in the height of the germinal epithelium (p<0.01), disorganisation of germ cells, desquamations of immature germ cells, formation of giant multinucleated cells, and significant (p<0.01) expansion of the interstitium. At the level of transmission electron microscopy, there were observed basement membrane irregularities in seminiferous tubules, vacuolation of the cytoplasm and adversely affected organelles in Sertoli cells, germ cells, Leydig cells, peritubular and endothelial cells. The tight junctions between adjacent Sertoli cells were often incomplete, and necrotizing germ cells were more numerous in experimental animals compared to controls. Enhanced necrotizations of germ cells proved by a Fluoro Jade C method, and declined germ cells proliferation confirmed by proliferating cell nuclear antigen analysis, were detected in MR exposed animals. Our results revealed that the prenatal exposure to MR had an adverse effect on the postnatal testicular development in rats.