The vertebrate limb
http://embryology.med.unsw.edu.au/
Use the resources on Mark Hill’s Embryology site at the University of New South Wales to explore limb development.

• What are the signals that control formation of a forelimb versus a hindlimb? (page 449 Wolpert text)
• Describe the type of homeotic transformation that mis-expression of the Tbx genes would produce.

Internal organs: insect tracheal system, vertebrate lungs, kidneys, blood vessels, heart, and teeth
www.indiana.edu/~anat550/embryo_main/
Visit this series of animated human organ systems during development. Discover how well you understand the formation of these systems through participation in the assessment of the site by taking a pre-test and post-test.

http://virtualhumanembryo.lsuhsc.edu
The Virtual Human Embryo project at Louisiana State University in Baton Rouge has developed a digital atlas of human development. Use the link on the left for the “Heirloom collection”, then again on the left, “The Human embryonic period”. You will find a combination of photographs and drawings of human development, broken down into the 23 Carnegie stages. Go through them one by one and try to understand what is being shown. For example:

• Where in the female reproductive system does stage 1 occur?
• In the stage 5 photographs, what are we looking at? What is the background on which the embryo is sitting?
• In the stage 10 photograph, identify the neural tube and the somites.
• In the later embryos, can you relate this lateral view of the development of the face to the frontal view you explored in the anatomy site from Indiana U (www.indiana.edu/~anat550/embryo_main/)?

www.med.unc.edu/embryo_images/
Embryologist Kathy Sulik and radiologist Peter Bream of the University of North Carolina, Chapel Hill, developed this illustrated, nine-unit tutorial of normal and abnormal mammalian development. In sequences of labeled electron micrographs and animations, the eyes, ears, heart, and other structures sprout and take shape. Watch a furrow on the embryo's back close to form the spinal cord, or slice through the center of an embryo to reveal the looping heart.