It’s easy to be overwhelmed when learning about all that goes on during development. Then, you learn about the regularity and geometry seen throughout development (and biology in general) and that anxiety is washed away. I love seeing regular patterns and shapes throughout the biological world, and today’s image is a nice example of precision during development.
During development of a frog’s skin, there are two layers of cells. The top layer is made of cells that secrete mucus, and the bottom layer is made of cells that have cilia, or small hair-like projections. During skin development, these two layers intercalate and the resulting organization of mucus-secreting and cilia-containing cells is precise and predictable. A recent paper identified a role for a receptor protein called dystroglycan (Dg for short) in skin development. Dg is a critical receptor of basement membranes, which are regions that underlie tissues to provide signals and mechanical support. According to Sirour and colleagues, Dg gene expression is found in the bottom layer of cells in the developing skin of frog embryos. Loss of Dg function results in the disruption of skin development, specifically cell intercalation, cell-cell adhesion, and organization of the underlying matrix. As seen in the images above, the skin of control frog embryos have a precise flower-like arrangement of cells—a cilia-containing cell is surrounded by mucus-secreting cells (top). When Dg levels were reduced (bottom), that organization is disrupted.
Sirour, C., Hidalgo, M., Bello, V., Buisson, N., Darribere, T., & Moreau, N. (2011). Dystroglycan is involved in skin morphogenesis downstream of the Notch signaling pathway Molecular Biology of the Cell, 22 (16), 2957-2969 DOI: 10.1091/mbc.E11-01-0074