Comparable advances in bioimaging further enable us to visualize tissue-specific biomineralization such as that demonstrated in dentin and enamel. We now are able to visualize and eventually understand the intriguing world of atoms, molecules and motif interactions in health and disease. We know that each of us begins life s journey as a single cell a little smaller than 1 mm in diameter. Each somatic cell contains the genetic lexicon for becoming a human being. During development, cells replicate and communicate, change size and shape, and then diversify and organize into tissues, organs and systems.
Some cells express programmed cell death apoptosis along a particular developmental scheme.
Eventually, as a mature adult, each of us contains approximately 100 trillion cells, and each of these cells contains all of the genes that were found in our first cell. During the last few years, we have learned a great deal about the structure and functions of individual human genes, and we have gained a molecular under-standing of our internal and external environments. Much of the world was not prepared for the news from Scotland last year. A specialized and differentiated cell from an adult sheep udder was shown to provide a program in the form of genomic DNA that could direct the development of an embryonic sheep. The result of this cell biology manipulation, when implanted in a sheep foster mother, eventually resulted in the delivery of Dolly, a normal lamb with the genetic characteristics of the adult sheep that donated the udder cell.