SPATIAL AND TEMPORAL DISTRIBUTION OF INDIAN HEDGEHOG MESSENGER-RNA INTHE EMBRYONIC MOUSE MANDIBLE

Hedgehog genes are involved in pattern formation during embryonic deve lopment. A recent report showed that Sonic hedgehog is expressed in th e mouse mandible in the presumptive incisor region. In the present stu dy, Indian hedgehog (Ihh) transcripts were present from gestational da y 9 to 14 in the mouse mandible (reverse transcription/polymerase chai n reaction analysis). Ihh mRNA was present in the dental lamina in bot h incisor and molar regions and in the developing whiskers (in situ hy bridization). Ihh may be involved in the site-specific proliferation o f mandibular epithelium during the formation of the dental lamina. Thi s is consistent with the observation that endogenous synthesis of reti noic acid is necessary for the initiation of odontogenesis and that re tinoic acid induces hedgehog expression. Copyright (C) 1996 Published by Elsevier Science Ltd.