|
|
|
Rich Schneider, PhD
Craniofacial Morphogenesis and Evolution
|
|
|
|
Morphogenesis is a dynamic developmental process through which cells and tissues differentiate and grow into the complex anatomical structures that form an organism. In order for individual neural, skeletal, muscular, and vascular components to achieve their proper size, shape, orientation, and functional integration, embryonic progenitor populations require appropriate spatial and temporal signals. Our research focuses on the extent to which the neural crest, which is a mesenchymal stem cell population, serves as a source of spatiotemporal patterning information during craniofacial morphogenesis. The special patterning abilities of the cranial neural crest have been recognized for more than fifty years but precise molecular mechanisms through which they exert their effects remain obscure. Cranial neural crest cells originate along the dorsal margins of the developing neural tube, and they migrate extensively throughout the head. Their derivatives include cartilage, bone, dentine, sensory ganglia, glia, melanocytes, meninges, and a variety of connective tissues. Transplant experiments in diverse vertebrate taxa have offered persuasive evidence that cranial neural crest cells possess inherent programmatic information governing the anatomy of their own derivatives, especially cartilages and bones of the face and jaws.
In my lab, we have been developing an experimental chimeric system using two distinct avian species, quail and duck. This approach exploits the fact that as embryos, quail and duck are morphologically distinct and have considerably different rates of maturation, which provides a novel method for manipulating signals being conveyed between skeletal precursor cells and adjacent tissues such as muscles, nerves, and epidermis. In particular, exchanging premigratory cranial neural crest cells between quail and duck embryos permits progressively asynchronous donor mesenchyme and host tissues to interact with one another continuously from the moment they first meet. Consequent neural crest-mediated changes to molecular and histogenic programs of craniofacial development can then be observed. We are finding that within resultant chimeras, donor neural crest mesenchyme executes autonomous molecular programs and regulates gene expression in adjacent host tissues. This in turn, establishes when derivatives of the donor and those of the host undergo differentiation, and determines the size, shape, and location of anatomical structures from both the donor and the host. Thus, neural crest mesenchyme functions as a primary source of spatiotemporal patterning information during craniofacial development, and in this capacity has likely played an essential role in facilitating morphological change during the course of evolution. Identifying precise signaling mechanisms through which these mesenchymal stem cells exert their affects will be critical for devising molecular-based therapies that can induce repair and regeneration of anatomical complexes affected by congenital defects, disease, and trauma.
|
|
Eames, B. F., N. Allen, J. Young, A. Kaplan, J. A. Helms, and R. A. Schneider. 2007. Skeletogenesis in the swell shark Cephaloscyllium ventriosum . Journal of Anatomy , 210:542-554.
Schneider, R. A. 2007. How to tweak a beak: Molecular techniques for studying the evolution of size and shape in Darwin's finches and other birds. BioEssays , 29(1):1-6.
Noden, D. M. and R. A. Schneider. 2006. Neural Crest Cells and the Community of Plan for Craniofacial Development: Historical Debates and Current Perspectives. In Neural Crest Induction & Differentiation . J. Saint-Jeannet (editor). Advances in Experimental Medicine and Biology, Volume 589. Landes Bioscience. Georgetown. 1-31.
Ye, L., T. Q. Le, L. Zhu, Q. Yan, K. Butcher, R. A. Schneider, W. Li, P. K. Den Besten. 2006. Amelogenins in Human Developing and Mature Dental Pulp. Journal of Dental Research , 85:814-818.
Haggstrom, A. N., E. J. Lammer, R. A. Schneider, R. S. Marcucio, and I. J. Frieden. 2006. Patterns of infantile hemangiomas: New clues to hemangioma pathogenesis & embryonic facial development. Pediatrics , 117:698-703.
Schneider, R. A. 2005. Developmental mechanisms facilitating the evolution of bills and quills. Journal of Anatomy.
Eames, B F. and R. A. Schneider. 2005. Quail-duck chimeras reveal spatiotemporal plasticity in molecular and histogenic programs of cranial feather development. Development. 132:1499-1509.
Radlanski, RJ, Renz, H, Lajvardi, S, and R. A. Schneider. 2004. Bone remodeling during prenatal morphogenesis of the human mental foramen. European Journal of Oral Sciences. 112:301-310.
Helms, J. A. and R.A. Schneider. 2003. Cranial skeletal biology. Nature, 423:326-31.
Schneider, R. A. and J. A. Helms. 2003. The cellular and molecular origins of beak morphology. Science, 24 January. 299:565-568
Schneider, R. A., D. Hu, J. L. R. Rubenstein, M. Maden, and J. A. Helms. 2001. Local retinoid signaling coordinates forebrain and facial morphogenesis by maintaining FGF8 and SHH. Development, 128:2755-2767.
Schneider, R. A., D. Hu, and J. A. Helms. 1999. From head to toe: conservation of molecular signals regulating limb and craniofacial morphogenesis. Cell & Tissue Research, 296:103-109.
Schneider, R. A. 1999. Neural Crest Can Form Cartilages Normally Derived from Mesoderm During Development of the Avian Head Skeleton. Developmental Biology, 208(2):411-455.
Smith, K. K. and R. A. Schneider. 1998. Have Gene Knockouts Caused Evolutionary Reversals in the Mammalian First Arch? BioEssays, 20(3):245-255.
information last updated May 2007 |
|
|
|
 |
|
|
