Prenatal expression of growth hormone receptor/binding protein and insulin-like growth factor-I (IGF-I) in the enamel organ. Role for growth hormone and IGF-I in cellular differentiation during early tooth formation?
Immunohistochemistry was used to study the ontogeny of GH receptor/binding protein (GHR/BP) and IGF-I from the 13-day-old embryo (E13) to the E19 rat fetus in the developing incisor and molar. Analysis of serial sections revealed diffuse staining of GHR/BP and IGF-I at the bud and early cap stages within both the mesenchyme of the dental papilla and the ectodermal-derived enamel organ. Just before transition to the cap stage, immunoreactivity of GHR/BP and IGF-I increased in the epithelial bud and extended to the condensed dental mesenchyme. At the cap stage, the dental epithelium showed an intense expression of GHR/BP and IGF-I, whereas the dental mesenchymal cells showed very weak staining. The inner enamel epithelium and the outer enamel epithelium were positive for both GHR/BP and IGF-I in the bell stage. Differentiating ameloblasts, odontoblasts and the secretory ameloblasts and odontoblasts continued to express GHR/BP and IGF-I in incisors. These findings support the premise that growth hormone and IGF-I may play a role in embryonic tooth development by regulating the epithelial-mesenchymal interactions that influence events in growth and cytodifferentiation.
Department of Oral Biology and Pathology, University of Queensland, Brisbane, Australia.
B K
BK
Joseph
N W
NW
Savage
W G
WG
Young
M J
MJ
Waters
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis* / Q000378:metabolism / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D003743:Dental Enamel / Q000737:chemistry* / Q000196:embryology / Q000502:physiology; D005260:Female; D005333:Fetus / Q000737:chemistry; D007150:Immunohistochemistry; D007335:Insulin-Like Growth Factor II / Q000032:analysis* / Q000378:metabolism / Q000502:physiology; D009805:Odontogenesis / Q000502:physiology; D051381:Rats; D011917:Rats, Inbred Lew; D011986:Receptors, Somatotropin / Q000032:analysis* / Q000378:metabolism / Q000502:physiology
D002352:Carrier Proteins; D011986:Receptors, Somatotropin; D007335:Insulin-Like Growth Factor II; C051815:somatotropin-binding protein