Fragile Eggshells

I was talking in my physiology course yesterday about the development of the human fetus, when I started to describe several different reasons for how women are significantly more susceptible compared with men on developing osteoporosis.   One of the myriad of reasons that I described was related to an association of the number of children a women gives birth to during her reproductive lifespan.  The more children a women has (especially if she consumes a calcium modest diet), the greater her chance of having osteoporosis later in life.  I went on to further explain that physiologically, there are biochemical mechanisms that occur during pregnancy that will if needed, leach out calcium from the woman's own skeletal system to ossify and strengthen the skeletal system of the fetus.

I went on to further describe that this is similar to a process seen in birds.  The chicken egg, for instance..... when the developing chick grows within the egg, it will form vascular fields near the egg shell specifically to acquire oxygen from the external environment through diffusion through the shell..... but the vascularization will also allow the developing chick to absorb calcium from the shell to use in the creation of its own bones in its skeletal system.  I mentioned then how late in the incubation period for the chicken egg, the shell is structurally much weaker and more fragile. 

I talk about this calcium relationship every semester.  But, it seemed especially interesting to students in my class this semester, and we spent a good additional 15 minutes discussing their questions, thoughts, and ideas about both chickens and about the disease of osteoporosis.   It was interesting to hear their opinions and their ideas, and even their misconceptions on some of these ideas. 

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