You might wonder what frogs have to do with developmental biology. The large female and the smaller Xenopus, the African Clawed Frog, in the photo is the sweetheart of developmental biologists. Their embryos have been used for decades in studies designed to understand fertilization and early development. 

This is a composite confocal image of a early Xenopus embryo I took this summer with the membrane labeled with enhanced green fluorescent protein. The boundaries between adjacent cells are clearly visible.