Egg-less Chicken Embryos and Real Science

Trying a lab for the first time is a great learning experience.  Sometimes we use labs that "work", but it doesn't give us the chance to think through how we could improve an experiment or procedure we've tried to figure out. The students hear from me that real science is trying experiments over and over, making tweaks, and sometimes going back to the drawing board altogether. Trying to hatch egg-less chicks has been a great experience in working on procedure.

Students had a chance to try again when the yolk broke, or the egg was rotten, and because of it, they became more confident in what they were doing. Finally having some success was very exciting. And to see the embryo development that happened in just one day was amazing. I am regretting not going into school on Saturday since when I checked Sunday our best embryo had made so much progress.  I don't know that it will progress much further though, since it looks like the yolk has broken.  I'm still impressed with the development that we were able to see, and now we have more ideas of what to try to make it better.

One of the problems we encountered was too many cups in the oven--next time, no more than 7 since cramming 8 in lifted some of the petri dishes. The embryos with the lifted petri dishes dried out and died. Also, we should only use the eggs with embryos that have made it to the stage of seeing the heart beating.  The younger embryos did not progress well for us. I'm also hypothesizing that it would be better to err on the side of the oven temperature being on the low side instead of on the high side. One last change was to not push down the plastic wrap as low, so the egg is closer to the top of the cup. The theory is that it will leave less air for the moisture of the egg to evaporate into. We're trying to stop dry-out.

Hatching Chickens Outside Their Shells

At the end of the school year last year, one of my students sent me the video of the Japanese students who hatched a chicken in a cup with plastic wrap and no shell.  It looked fascinating and used readily available materials. I decided that we'd give it a try this year when we got into embryonic development.

I did some research and found a couple of helpful resources, one from the Cooperative Extension of the University of Connecticut and one from a text by Cynthia J. Fisher.  We did a slight modification of the procedures to compensate for using an oven. It's really a drying oven that the Chemistry and previous AP Bio teacher figured out where to turn the knob to keep it at 37ish degrees Celsius for the bacteria labs we do.  I pre-heated it on Monday so it was at 38 degrees Tuesday morning.

Note the duct tape holding it shut since we have it a little over-full.

There are several school families who keep chickens. A couple of them have roosters and were more than willing to provide us with fertilized eggs. This past Tuesday, we put the eggs in our "incubator". We added a few more to the incubator on Wednesday--long story, involving an extended school bus ride. =)

After incubating for two and a half days, we cracked the eggs during our Thursday afternoon lab. The yolk of the first egg broke in the process, then the next was rotten. (We had been warned about that potential because of finding some rotten eggs by the "brooding" chickens.) One more broken yolk, and then we had success. I think it helped to have to repeat the process since students got more comfortable with it as we went.  In the end we cracked open a couple of extras and took two videos of hearts beating that we could see. We put them into their "cup homes" for the duration of their development.

To make the homes for the chicks, we used Styrofoam coffee cups, poked a pencil hole in opposite sides of the cup, poured water into the cups up to the pencil holes to provide extra humidity, placed cheap plastic wrap (in hopes the cheap stuff would be more "breathable") over the cup and pushed it down to form a sling, held it in place with a rubber band, and covered it with the bottom of a petri dish.  Eight cups is a tight fit in our little oven, so not all of the petri dishes set well, but so far it appears to work OK.

Today, we checked our chicks-in-a-cup and were amazed by the embryonic development occurring in just under 24 hours!  If I had to guess, students would say it was one of their favorite labs.  And we're hoping it will continue for at least a week, maybe more. The students are voting for all 21 days of course. When we finish, for their lab reports, students will put together a movie of the process. I've included a video of what we've done so far.