Basement membranes are crucial for proper olfactory placode shape, position and boundary with the brain, and for olfactory axon development.

Despite recent progress, the complex roles played by the extracellular matrix in development and disease are still far from being fully understood. Here, we took advantage of the zebrafish mutation which affects Laminin γ1, a major component of basement membranes, to explore its role in the development of the olfactory system. Following a detailed characterisation of Laminin distribution in the developing olfactory circuit, we analysed basement membrane integrity, olfactory placode and brain morphogenesis, and olfactory axon development in mutants, using a combination of immunochemistry, electron microscopy and quantitative live imaging of cell movements and axon behaviours.

Laminin γ1-dependent basement membranes are instrumental to ensure proper olfactory placode shape, position and boundary with the brain, as well as olfactory axon development.

Despite recent progress, the complex roles played by the extracellular matrix in development and disease are still far from being fully understood. Here, we took advantage of the zebrafish mutation which affects Laminin γ1, a major component of basement membranes, to explore its role in the development of the olfactory system. Following a detailed characterisation of Laminin distribution in the developing olfactory circuit, we analysed basement membrane integrity, olfactory placode and brain morphogenesis, and olfactory axon development in mutants, using a combination of immunochemistry, electron microscopy and quantitative live imaging of cell movements and axon behaviours.

Intertissue mechanical interactions shape the olfactory circuit in zebrafish.

While the chemical signals guiding neuronal migration and axon elongation have been extensively studied, the influence of mechanical cues on these processes remains poorly studied in vivo. Here, we investigate how mechanical forces exerted by surrounding tissues steer neuronal movements and axon extension during the morphogenesis of the olfactory placode in zebrafish. We mainly focus on the mechanical contribution of the adjacent eye tissue, which develops underneath the placode through extensive evagination and invagination movements.

Apoptosis and cell proliferation during metamorphosis of the planula larva of Clytia hemisphaerica (Hydrozoa, Cnidaria).

Background: Metamorphosis in marine species is characterized by profound changes at the ecophysiological, morphological, and cellular levels. The cnidarian Clytia hemisphaerica exhibits a triphasic life cycle that includes a planula larva, a colonial polyp, and a sexually reproductive medusa. Most studies so far have focused on the embryogenesis of this species, whereas its metamorphosis has been only partially studied.