http://www.standupgirl.com/inside/tour/body.html
Here is just part of the story.
TWO MONTHS
By 8 weeks the embryo grows to 1/2 an inch, the major muscles system develops and she moves gracefully like a good swimmer although you can't feel it yet. This tiny human is perfectly developed with long, tapering fingers, feet and toes and whose skin is almost transparent with a highway of delicate arteries and veins visible to the ends of the fingers.
By 10 weeks 20 tiny baby teeth are forming in the gums, she squints, swallows, moves her tongue, and if you stroke her palm, will make a tight fist. The toes will develop in the next few days and brain waves can be measured.
Did ya know?
By nine weeks the developing baby can hiccup and react to load noises. This might explain why I still hiccup at loud concerts :-)
THREE MONTHS
By the second trimester, your baby is now in its fetal stage and measures 2 1/2 to 3 inches in length. Fully formed the heart rate can be heard with a special instrument called a Doppler.
Here's a great quote: "The body of the unborn baby is more complex than ours. The preborn baby has several extra parts to his body which he needs only so long as he lives inside his mother. He has his own space capsule, the amniotic sac. He has his own lifeline, the umbilical cord, and he has his own root system, the placenta. These all belong to the baby himself, not to his mother. They are all developed from his original cell."
Day & Liley, The Secret World of a Baby, Random House, 1968, p. 13
Did ya know?
Just as adults the baby at the fetal stage experiences the rapid eye movement (REM) sleep of dreams. Okay... why did you say you like REM's music?
FOUR MONTHS
Your baby is coated with soft downy hair called "lanugo" and comes in at 7 inches in length and weighing 6 to 7 ounces.
Fine hair, eyelashes, and fingerprints are all complete and this girl is all made up :-).
Did ya know?
Awake or asleep, the human fetus moves 50 times or more each hour exploring her warm, wet compartment by touch. Reports indicate she touches her hand to her face, places one hand on the other hand, clasps her feet, places her hand to the umbilical cord and sometimes walks around the womb by pushing off with her feet. Ever wonder where we got those funky dance aerobics from?