Questions about the unfertilized egg

Q: The real question I have for you has to deal with an animal physiology class I took last semester. We had to find the total pore area of a hen egg. To do this we had to calculate the surface area of an egg (this is the part that stumped us). We made approximations using calculus but if you have any insight as to calculate the surface area of an egg, your input would be greatly appreciated. [Question submitted by scarey@agt.net]

A: You could compute the surface, volume, etc. using calculus methods if you had a functional description of the shell geometry. Alternatively, one can use stereological methods. This would involve numerical integration of information from multiple slices. Since this is essentially a Simpson's rule procedure (each slice is assumed to be rectangular in cross section, or possibly trapezoidal) one needs as many thin slices as possible for accuracy. For example, measure the perimeter (or area) on each slice, assume cylindrical or conical sections of height = slice thickness, and sum the area (or volume) over all slices. One could compare results obtained with each of the three principal views - they should all agree in the limit of thin slices.

Q: Please help, we were having a major family "discussion" regarding whether a chicken needs to be fertilized by the rooster before laying an egg? It seems we support two schools of thought, the first is a hen will lay an egg if not fertilized by a rooster, however the egg will not grow into a chicken. The second theory is the hen needs to be fertilized by the rooster to even lay an egg. If proper conditions apply than the egg will grow into a chicken. Which is correct? [Question submitted by afriend@adnetsol.com]

A: The hens don't need the roosters to lay an egg. In fact, most hens that lay grocery store eggs have never seen a rooster. An unfertilized egg will not grow into a chicken.

Questions about the developing chick

Q: What is the latebra? [Question submitted by jkharper@prairienet.org]

A: The latebra is an area of white yolk located in the center of the yolk. It is lower in fat and therefore stands out as a bright white area in many of our MR images. In some of the images, you can see a thin strand of the latebra which extends from the center to the surface of the yolk where the embryo is located. The specific function of the latebra is uncertain but it may act as a central structure around which the additional layers of the yolk are formed.

Q: The eggs seem to be small. How can their big feet, eyes and body all fit in there for 21 days? Why does the embryo absorb the yolk sac? [Question submitted by a middle school Chickscope student]

A: The chick doesn't "eat" anything for 21 days (and a couple more after it hatches, usually). It lives off the "fat of the land", using the yolk for energy and building materials. Eventually it all gets used up, which is a good thing, since that leaves room for the chicken.

Check out the Egg Chemistry page for more information about the yolk.