Day 3: Say Cheese!
A Microscope's View
How has today's photomicrograph of a 72 hour
chick embryo changed from yesterday's
photomicrograph of a 48 hour chick embryo?
The head and upper body of the embryo has
curved even more and the tail is beginning to
curve as well. The ear is clearly visible.The
two parts of the embryonic eye, the lens and the
optic cup surrounding it, are also
distinguishable. Different portions of the brain
can be seen. There are about 30 somites at this stage.
Because the heart grows so
quickly at this stage, it cannot fit inside the
embryo. The tight fit causes the heart to loop
and twist as it grows. The rest of the body
eventually turns to lay on its left side, giving
the heart more room.
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