Understanding embryonic development is a great biological puzzle. What we're trying to figure out is how a single cell, the fertilized egg, gives rise to a multicellular organism like a fly, sea urchin, frog, bird, or human. For those of us who work with developing embryos, we never lose our sense of wonder at this remarkable process. There is a new vocabulary to learn and key processes to understand, but they are not extensive. The greatest difficulty students have is visualizing the changes that occur in a three dimensional embryo, as well as, the changes that occur in an embryo over time.
Direct observation is the ideal method for visualizing developing embryos.
Students typically watch sea urchin, fly, frog and chick embryos develop in lab classes. To overcome these shortcomings, we are gathering videosequences of developing embryos from developmental biologists. We cannot dissect an embryo because it's too small. To see what's going on inside, we have to look at serial sections of embryos. Serial sections are where we slice an embryo as if it were a sausage.