Rothman-Simeone and Herkowitz’s

The embryologic development of the human spine is an enormously complex process that is only partially understood. Differentiation of the pluripotent tissues of the embryo leads to early formation of a repetitive segmented vertebral structure.

Because the embryo is exquisitely susceptible to malformation and developmental error, each step of formation is critical.1-4 Familiarity with these various steps can be helpful in understanding not only congenital syndromes, but also the possible developmental role concerning predisposition to some degenerative spinal processes, typically considered “wear and tear” conditions.5,6 he continuously expanding understanding of the genetic basis of life, with the genetics of spinal development no exception, has aided the understanding of these syndromes.7-13 Fundamental to understanding spinal embryology is the concept of metamerism. In principle, metamerism is the development of a highly specialized organism, with multifunctional organ systems, from many anatomically similar segments arranged in a linear fashion. his is particularly easy to conceptualize in the spine because the fully developed spine comprises numerous units with similar shape, arrangement, and function. Metamerism also pertains to the development of the appendages from the metameres, however, which do not have such repetitive arrangement of consecutive units.