scholarly journals Cell lineage of primary and secondary enamel knots

2005 ◽  
Vol 233 (3) ◽  
pp. 754-759 ◽  
Author(s):  
E. Matalova ◽  
G.S. Antonarakis ◽  
P.T. Sharpe ◽  
A.S. Tucker
Keyword(s):  
Cell Lineage ◽  
Enamel Knots

Enamel Knots as Signaling Centers Linking Tooth Morphogenesis and Odontoblast Differentiation

2001 ◽  
Vol 15 (1) ◽  
pp. 14-18 ◽  
Author(s):  
Irma Thesleff ◽  
Soile Keranen ◽  
Jukka Jernvall
Keyword(s):  
Tooth Development ◽  
Experimental Studies ◽  
Cell Lineage ◽  
Signaling Molecules ◽  
Enamel Knot ◽  
Odontoblast Differentiation ◽  
Dental Papilla ◽  
Dental Epithelium ◽  
Tooth Morphogenesis ◽  
Enamel Knots

Odontoblasts differentiate from the cells of the dental papilla, and it has been well-established that their differentiation in developing teeth is induced by the dental epithelium. In experimental studies, no other mesenchymal cells have been shown to have the capacity to differentiate into odontoblasts, indicating that the dental papilla cells have been committed to odontoblast cell lineage during earlier developmental stages. We propose that the advancing differentiation within the odontoblast cell lineage is regulated by sequential epithelial signals. The first epithelial signals from the early oral ectoderm induce the odontogenic potential in the cranial neural crest cells. The next step in the determination of the odontogenic cell lineage is the development of the dental papilla from odontogenic mesenchyme. The formation of the dental papilla starts at the onset of the transition from the bud to the cap stage of tooth morphogenesis, and this is regulated by epithelial signals from the primary enamel knot. The primary enamel knot is a signaling center which forms at the tip of the epithelial tooth bud. It becomes fully developed and morphologically discernible in the cap-stage dental epithelium and expresses at least ten different signaling molecules belonging to the BMP, FGF, Hh, and Wnt families. In molar teeth, secondary enamel knots appear in the enamel epithelium at the sites of the future cusps. They also express several signaling molecules, and their formation precedes the folding and growth of the epithelium. The differentiation of odontoblasts always starts from the tips of the cusps, and therefore, it is conceivable that some of the signals expressed in the enamel knots may act as inducers of odontoblast differentiation. The functions of the different signals in enamel knots are not precisely known. We have shown that FGFs stimulate the proliferation of mesenchymal as well as epithelial cells, and they may also regulate the growth of the cusps. We have proposed that the enamel knot signals also have important roles, together with mesenchymal signals, in regulating the patterning of the cusps and hence the shape of the tooth crown. We suggest that the enamel knots are central regulators of tooth development, since they link cell differentiation to morphogenesis.

A Review of the Natural Killer Cell Lineage in the Uterus of the Mouse and of the Pig

1994 ◽  
Vol 72 (suppl_3) ◽  
pp. 9-15 ◽  
Author(s):  
B. A. Croy ◽  
Z. M. Yu ◽  
G. J. King
Keyword(s):  
Natural Killer Cell ◽  
Natural Killer ◽  
Killer Cell ◽  
Cell Lineage
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