ASGSB 1999 Annual Meeting Abstracts

INITIATION OF MOLAR DEVELOPMENT IN MURINE FIRST ARCHES CULTURED IN A THREE-DIMENSIONAL SYSTEM. P.S. Williams, D. Montufar-Solis, and P.J. Duke. Dept. of Orthodontics, Dental Branch, UT Houston Health Science Center, Houston, TX.

The formation of the embryonic tooth is an excellent model for morphogenesis and cytodifferentiation. Its study has provided many important concepts in tissue interactions, induction, and the control of pattern formation by homeobox genes. Tooth development is divided into three phases: initiation, morphogenesis, and cytodifferentiation. For the two later stages of development, there exist culture techniques, which have allowed signaling molecules and genes to be identified. However, less is known about the genes and molecules in the first stage, in part, because there has not been a culture system able to support development of the jaws during the complex process of initiation. A new culture system that uses a rotating bioreactor developed by NASA, provides homogenous distribution of nutrients, waste, and gases, and little accompanying turbulence or shear force. In this study, entire first branchial arches with associated neural tube structures were excised from E10 embryonic mice and cultured inside the bioreactor. Controls were cultured in a classic Trowell type system. Samples were fixed every day for one week and sectioned for light microscopy. In the 2-dimensional Trowell system the morphology of the tissue was disrupted by gravity, which caused it to flatten onto the filter. This, added to the lack of nutrients to all parts of the tissue, compromised the development of the jaws. Samples cultured in the bioreactor maintained their 3-dimensional structure, and produced Meckel’s cartilage and tooth formation to the cap stage. This study demonstrates that the NASA bioreactor provides a more in vivo-like culture system, which supports the intricate initiation phase of tooth development.

(Supported in part by NIH/NIDR Training Grant T35 DE 07252.)

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