Week 1 1/4-1/10 Role of Sonography in Obstetrics
Week Two 1/11-1/17 Fertilization and The Use of U...
Week Three 1/18-1/24 The Fetal Environment: Umb. C...
Week Four 1/25-1/31 2nd Trimester Evaluation &am...
Week Five 2/1- 2/7 Fetal Thorax
Week Six 2/8-2/14 Fetal Head and Face
Week Seven 2/15-2/21
Week Eight 2/22-2/28 Fetal Abdomen and Urogenital ...
Week Nine 3/1-3/7 Fetal Skeletal System
Week Ten 3/8-3/14
Week Eleven 3/15-3/21
Week 12 3/22-3/28
Development of the Placenta Villi
Here is a great site with this page showing clear examples of how the placenta forms and and the different layers we need to know about.
Click http://www.embryology.ch/anglais/fplacenta/villosite06.html link to open resource.