Animals in utero

According to this CNET article, scientists have used advanced ultrasound technology to capture three-dimensional images of animals inside the womb. Below are some of the pictures from the article. The scientists also hired artists to create models of the developing mammals (similar to production for a computer animation film), to create a video of the animals throughout gestation (click here for a brief preview). The video is featured in National Geographic's special entitled In the Womb: Animals.

The Asian elephant fetus (shown below) is unique for its 22-month gestation period, the longest pregnancy of all mammals. In the fetus, the elephant develops a unique mammalian feature called nephrostomes, or funnel-like ducts in the kidneys. These ducts can be found in freshwater fish and frogs, leading scientists to believe that elephants may have evolved from aquatic beginnings, when they used their trunks as snorkels. In fact, elephants can swim more than 15 miles without stopping by using their trunks to breathe!



Pictured below is a dog in the womb. At 60 days in the womb, three days before birth, the puppy has developed a full coat of hair, with nails and paw pads, and the body is covered with touch-sensitive nerve endings. It has also displayed its characteristic panting in the fetus, a behavior that helps the dog regulate its own body temperature in the absence of ample sweat glands.



Below is a dolphin in the womb. At one month in the womb, dolphins develop tiny leg-like limb buds that vanish within two weeks, and the animals swim in amniotic fluid for the next 11 months of gestation. Scientists say that evolutionary trick is a sign that the highly intelligent mammals descended from dog-like land creatures. At nine months, the dolphin has no more room in the mother's uterus, so the fetus curls inside the uterine wall. Hairs like tiny whiskers on the dolphin will fall out after birth as a result of water pressure, but the pores will remain open. At birth, the dolphin can see and swim, and has the musculature to follow its mother to the top of the ocean to get its first breath. When dolphins breathe, they exchange 80 percent of the oxygen in their bodies. Humans, in contrast, swap out only 17 percent.