Day 4: Our focus today was on collecting data to determine if, in fact, we supported our hypotheses. Any pigment that should be developing in the embryos, should, at this point, be visible. Tomorrow will be our final check. Several groups had embryos hatch out of their chorions today; the fluttering two-chambered heart was visible. Wow! (Zebrafish have the ability to regenerate heart tissue; something that humans cannot do. This is one trait that researchers are interested in learning about to see if it can be applied to human cardiac care.) Classroom conversations today included comparisons of dominant vs recessive alleles, homozygous vs heterozygous genotypes, and random, wonderful middle school tangents into the murky world of bioethics and genetic engineering.