Origin of cells for connective tissues of skull and face ...( With improved resolution tissue-spec...)

With improved resolution, tissue-specific molecular markers and precise timing, University of Oregon biologist James A. Weston and colleagues have possibly overturned a long-standing assumption about the origin of embryonic cells that give rise to connective and skeletal tissues that form the base of the skull and facial structures in back-boned creatures from fish to humans.

Weston and co-authors from the Max Planck Institute of Immunology in Germany and the French National Scientific Research Centre at the Curie Institute document their potentially textbook-changing case in an article appearing online this week (May 19-23) ahead of regular publication in the Proceedings of the National Academy of Sciences.

The cells in question, they argue, do not come from a portion of embryonic neural epithelium called the neural crest, as widely believed, but rather from a distinct thin layer of epidermal epithelial cells next to it. "Our results," Weston said, "could lead to a better understanding of the etiology of craniofacial defects, as well as the evolution of the head that distinguishes vertebrates from other creatures."

The neural crest was first identified by classical embryologists in the late 19th and early 20th centuries and has been one of the most studied embryonic tissues. Conventional wisdom says that the neural crest gives rise to skeletal and connective tissue of the head and face, as well as a wide diversity of other stem cells that migrate to many places in the vertebrate embryo, where they spawn the cells that create the peripheral nervous system, and pigment cells in skin and hair (or scales and feathers).

The new study is part of research done over 25 years in Weston's quest to understand early development of the neural crest and explore alternative explanations for sometimes differing findings involving its assumed cell lineages. Weston noted that mutations in mice that adversely affected development of the periph
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