In its documentary Extraordinary Animals In The Womb, National Geographic captured rare highly detailed images of animals at various stages of gestation. Now you can see fetal dog, elephants, penguins, and dolphins still inside the womb.
Using advances in scanning and imaging technology to trace the gestational paths of animals outside the human family, the documentary footage is actually a combination of digital photography, scans, and computer-generated models. The filmmakers took detailed scans of the animal's wombs, then had the model makers recreate every blood vessel and whisker. The resulting images, while not direct photographs, are, according to the researchers, accurate representations of what goes on inside these creatures' wombs. You can read more about it in the Daily Mail.