The Visible Embryo, informational site at NIH:  http://www.visembryo.com/

University of Vermont teaching modules for human embryology:  http://cats.med.uvm.edu/cats_teachingmod/embryology/cats_embryo_home.html

Ultrasound image galleries for obstetrics and gynecology:  http://www.obgyn.net/us/img_gal.htm

Ultrasound image gallery for human development:  http://www.obgyn.net/us/gallery/gallery.htm

Gray's Anatomy OnLine: http://www.bartleby.com/107/ illus502.html

Fetal circulation by cardiac catheterization:  http://user.gru.net/clawrence/vccl/chpt1/fetcirc.HTM

Gray's Anatomy, Embryology, Placental Development OnLine: http://www.bartleby.com/107/12.html