Embryology

WebLecture Topics

• Development of a Zygote
• Development of a Human Embryo

Rather than duplicate the information in the text, I'm going to point you at some of the excellent websites available that have animations or videos of processes in the formation of the embryo.

Development of the zygote

Much of our knowledge of zygote development to blastula and gastrula depends on studies of sea urchins. For obvious reasons, close studies of human embryos at this state pose ethical issues, so we look for other species with similar development patterns.

The University of Wisconsin supports a good site explaining why we study sea urchins and the results of those studies. Pay particular attention to the sections on cleavage and gastrulation, and watch the movies!

Development of the Human Embryo

Here is a short video on human embryonic development (HHMI BioInteractive site.). Note the brief brightening at the moment of fertilization. This "zinc spark" occurs when a calcium influx causes the ovum to dump zinc ions as it responds to penetration by the sperm.

The Interactive Prenatal Development Timeline at the Endowment for Human Development has hundreds of pictures organized by week of human fetal development. Take a look at the detailed list of events each week.

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