1Department of Perinatology, Institute for Developmental Research, Aichi Prefecture Colony, 713-8 Kamiya-cho, Kasugai, Aichi 480-03, and, 2Aichi Prefecture I Chita District Public Health Center, 88-2 Yawata Aza Arakonochi, Chita, Aichi 478, Japan
The importance of Purkinje-granule cell interaction for cerebellar development was repeatedly emphasized by many authors. Mutant animals such as weaver and pcd mouse were useful instruments to speculate the mechanisms of the interaction. In weaver mice, almost all the population of postmitotic granule cells fails to migrate and dies. Purkinje cells, however, exist in the underdeveloped cerebellum. The death of Purkinje cells occurs after synaptogenesis in pcd mutant mouse. Developed granule cells remain unaffected in the mouse. Gunn rat is another type of mutant animal whose Purkinje cells are severely damaged at initial stage of synaptogenesis. The Gunn rat is devoid of hepatic UDP-glucuronosyltransferase activity toward bilirubin and as a consequence shows hyperbilirubinemia. A preferential deposition of bilirubin on Purkinje cells occurs in Gunn rat infants at postnatal day 7, then the cells are severely damaged. Postmitotic granule cells lost companions for synaptogenesis and faile to migrate. Our recent studies show that some lectins temporarily bind to Purkinje and/or granule cells in the initial stage of synaptogenesis. The Purkinje-granule cell communications may be mediated by various glycoproteins.