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In the
proposed research, we will examine the effects retinoic acid
(RA) and poly-l-lysine have on inducing the cells of the
craniofacial region to undergo chondrogenesis.
Introduction
The general area of
research associated with our project is chondrogenesis in
chick embryos. Chondrogenesis occurs in three stages. They
are mesenchyme proliferation, condensation of the
precartilagenous mesenchyme, and differentiation of the
chondrocyte (Gilbert 1997). The initiation of cartilage
formation occurs when the dividing precartilagenous
mesenchyme cells of the embryo begin expressing
extracellular matrix proteins that tell them to condense
into nodules (Gilbert 1997). The cells in these nodules
become chondrocytes and begin secreting the proteoglycans
and collagen necessary for cartilage formation (Gilbert
1997).
Though the basic process of
chondrogenesis is common to all cartilage, different
cartilaginous cells exhibit both intrinsic and induced
variations of these processes (Smith, 1998). Each type of
cartilage forming region exhibits different patterns and
amounts of cartilage. Studies have been performed to compare
chondrogenesis of leg and wing mesenchyme to the
craniofacial regions of the chick.
Wedden et al.
recognized the striking parallels between chondrogenic
patterns of cells from the face and limb buds in
culture(1986). For example, cultures of facial cells and
limb bud cells both visually and cellularly resemble each
other. Both cultures contain a mixture of committed and
uncommitted cells. However, no experiments have been
performed which test the effects of RA and poly-l-lysine on
chondrogenesis in the craniofacial region of the chick,
especially in comparison to the limbs.
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