Pathogens and Passageways: Embryology Lab!

Yesterday afternoon we did a fantastic embryology lab with Dr. Bill Strausberger and John Literacki in the Zoology Classroom! When we walked in, there were nearly 100 eggs lined up along two tables! Literally. We saw white eggs, round eggs, speckled eggs, tic-tac-sized eggs, eggs bigger than my head, and just about everything in between!

Then John gave a really interesting lecture on the morphology of eggs and their anatomy plus more on the variability among bird species. Did you know that the capillaries and heart develop outside the embryo? Or that an egg twirls continuously while it forms inside the mother to prevent any inner components from sticking to the side of the shell? Or that embryos are wrapped in a "chalaza" membrane, which is similar to the way a candy wrapper is situated? Or that in regards to bird size to egg ratios, an ostrich lays one of the smallest eggs, and a hummingbird lays one of the largest?

And in a kiwi, its body is nearly the same size as the egg! Where are all of its organs in the egg then??

Some other cool facts:
- While the egg is forming and twirling, it scrapes cells from its mother's duct walls, so researchers can recover and study DNA from one of its unknown parents (as is the case for cowbirds)!

- Cliff-dwelling birds' eggs have pointed tips. As a result, if one falls out of a nest, it will roll in circles in relatively the same place, which minimizes the risk of it falling off the cliff!

Bill took a few chicken eggs out from the incubator (temporarily, of course) and put them on this really cool machine that can track the developing embryo's heartbeat!

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Embryology lab-time!

We each got to look at eggs in various stages of development with an egg candler, and we saw some of their baby organs!

Then we cracked them all open and got to estimate how old we thought each one was. It was so fascinating to see the progression of an undistinguishable organism into a nearly-developed chicken!