obsolete somitomere true Wikipedia:Somitomere FMA:85523 Around the same time that experimental embryology in avian systems was most productive in the context of vertebrate head development, researchers examining embryonic head morphology with the scanning electron microscope introduced the idea of cephalic 'somitomeres'. By removing the surface ectoderm from the head, they reported that the paraxial mesoderm was organized into pseudosegmental units resembling incompletely differentiated somites, which they called somitomeres (Meier 1979; Jacobson 1988, 1993; Jacobson and Meier 1984). Since then, however, there has been no clear evidence for somitomeres. It remains unclear how they relate to the epithelial cysts in the head mesoderm - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2895339/] Obsoleted definition: In the developing vertebrate embryo, the somitomeres are loose masses of paraxial mesoderm derived cells that form along each side of the neural tube towards the end of the third gestational week. The approximately 50 pairs of somitomeres begin developing in the cranial (head) region, continuing in a caudal (tail) direction until the end of week four[WP]. somatomere UBERON:0005727 head paraxial mesoderm