The Public Broadcasting Station (PBS) documentary Life’s Greatest Miracle (abbreviated Miracle, available at http://www.pbs.org/wgbh/nova/miracle/program.html), is arguably one of the most vivid illustrations of the making of new human life. Presented as part of the PBS television series
To study human evolution, researchers sometimes use microstructures found in human teeth and their knowledge of the processes by which those structures grow. Human fetuses begin to develop teeth in utero. As teeth grow, they form a hard outer substance, called enamel, through a process called amelogenesis. During amelogenesis, incremental layers of enamel form in a Circadian rhythm.
Leonardo da Vinci’s embryological drawings of the fetus in the
Tooth enamel contains relics of its formation process, in the form of microstructures, which indicate the incremental way in which it forms during enamel formation on teeth
Historically the exact age of human embryo specimens has long perplexed embryologists. With the menstrual history of the mother often unknown or not exact, and the premenstrual and postmenstrual phases varying considerably among women, age sometimes came down to a best guess based on the weight and size of the embryo.
Among his myriad scientific and artistic contributions, Leonardo da Vinci’s work in embryology was groundbreaking. He observed and diagramed the previously undemonstrated position of the fetus in the womb with detailed accompanying annotations of his observations.
The principal work of
SEC. 509. (a) None of the funds made available in this Act may be used for--
(1) the creation of a human embryo or embryos for research purposes; or