The morphogenesis and morphological development of molar are regulated by the interaction between odontogenic epithelium and mesenchymal tissues. And Type IV collagen molecules, the major component of the dental basement membrane, are composed of three alpha chains. Using indirect immunofluorescence on cryosections, we characterized the changes in protein localization of alpha 1 to 6 chains of type IV collagen during molar development in mice molar and human tooth germ.ICR mouse embryos (detection of vaginal plug: day 0) and newborn mice were used. Human tooth germ was kindly provided by Dr. Yamamoto of Ohu University. Rat monoclonal antibodies recognizing type IV collagen alpha chains were raised against synthetic peptides of non-consensus amino acid sequences of the human and mice alpha (IV) chains. These monoclonal antibodies were kindly provided by Shigei medical research institute. Both mice and human tooth germ, we detected conversions in localization and composition of type IV collagen alpha chains working with tooth germ development. These results imply that there are time and site specificity, which may be involved in tooth morphogenesis and the tooth germ development, in type IV collagen alpha chains.