Investigating the developing nervous system in Sepia embryos: a review of recent findings

Over the last few years, studies of Sepia officinalis embryos have provided new discoveries about the nervous system (NS) development in Cephalopods. Investigations into neurogenic genes expressions, like Sof-elav, permitted to identify proneural cells before their differentiation into neurons. Differentiated neurons have also been discovered in early organogenesis, even though the developing nervous architecture is still far from definitive. The functionality of these neurons remains to be demonstrated but it is highly probable that these cells are fully functioning neurons since Sepia embryos can react to external stimuli from within their egg capsule. Populations of neurons with different neurotransmitters have been described and associated to the development of sensory functions (visual and olfactory) or motor functions (chromatophore control). Studies about developmental gene expression patterns inside the developing nervous system also provided data about the establishment of embryological polarities and territories in Cephalopods.