The double skeleton staining method is among the methods which are particularly used on rats. In the literature, studies take place titled as the examination of the effects on fetus bones by giving various substances on pregnant rats. Two different types of ossification are described in the embryonic period called as intramembranous ossification and endochondral ossification. Different staining methods are used to determine this ossification. Studies in which binary skeletal staining have been used are formed in two groups as teratogenic studies and developmental studies.