Desarrollo de la microglía y respuesta a la fotodegeneración inducida por luz intensa en la retina de ratón

Résumé

Microglial cells are involved in the surveillance and cleaning of the central nervous system (CNS), in the immune reactions taking place in the nervous parenchyma, and probably also in the building of the mature organization of the CNS (Kreutzberg, 1996; Aloisi, 2001; Mallat et al., 2005). They are thought to originate from cells of mesodermal lineage that colonize the CNS (Cuadros and Navascués, 1998). Microglial cells adopt distinct morphological and immunophenotypical features in different situations, and it is useful to distinguish between three major types of microglial cells: Developing microglial cells, which are frequent during embryonic and postnatal development. Most of them are amoeboid cells and are therefore called amoeboid microglia. Mature microglial cells, which have a mature level of ramification, and are thought to be quiescent cells that survey the nervous parenchyma. Reactive microglial cells, which derive from mature microglial cells that face an insult in the CNS. Their activation is accompanied by changes in shape, with retraction of cell processes, and increased immunoreactivity (Streit et al., 1999). These types are thought to correspond to different developmental and functional states of the same cell. Moreover, microglial cells are not homogenously distributed throughout the CNS (Lawson et al., 1990; Mittelbronn et al., 2001), suggesting that past or present local factors influence the distribution and state of differentiation of microglial cells. There is evidence that microglial cells of the developing CNS are able to respond to various types of injury, although features of the microglial reaction differ between the developing and adult CNS (Graeber et al., 1998; Cuadros et al., 2000; Sánchez-López et al., 2005).