Implicación de las vías de señalización del ácido retinoico en la especificación del epitelio ótico durante el desarrollo embrionario de aves

Abstract

The inner ear is a complex three-dimensional sensory structure with auditory and vestibular functions. It originates from the otical placode (Sánchez-Guardado et al., 2014), which invaginates to form the otical cup, and subsequently detaches to generate the otocyst, an ovoid vesicular structure physically independent of the ectoderm from which it originates. The otic epithelium will originate all sensory elements of the adult membranous labyrinth and neuronal precursors (Álvarez and Navascués, 1990; Bissonnette and Fekete, 1996; Fekete and Wu, 2002; Sánchez-Guardado et al., 2009, 2011, 2013, 2014). The complexity of this organ depends on the cellular specification orchestrated by diffusible molecules from adjacent tissues and from the otic epithelium itself, to guide the differentiation of sensory zones. Through the action of various signalling pathways, epithelium compartmentalization and subsequent specification of differential target occurs at early stages of development. This process appears to be governed by region-specific regulatory genes, providing positional identity according to a compartment-based model (Brigande et al., 2000; Fekete and Wu, 2002; Bok et al. , 2007). Whether cellular differentiation occurs at the appropriate time and place depends on the coordination between extrinsic and intrinsic signals (Bok et al., 2007; Ohyama et al., 2007; Schimmang, 2007; Whitfield and Hammond, 2007; Kelly and Chen, 2009; Frenz et al., 2010; Ladher et al., 2010). The aim of this research work will be to describe the spatial-temporal expression patterns of different important molecules during the embryonic development of the inner ear of birds from Hamburger and Hamilton stages 18 to 32, and the implication of these expression patterns in the definition of the anteroposterior, latero-medial and dorsoventral axes. All this is linked to the morphogenetic changes of this complex three-dimensional structure, especially considering morphogenetic movements, cell migration, as well as different proliferation activity and cell death.