PAX-GENES EXPRESSION DURING HUMAN EMBRYON IC-DEVELOPMENT, A PRELIMINARY-REPORT

PAX-genes encode important transcriptional factors during embryogenesi s. They are aslo involved in human diseases, Waardenburg syndrome, Ani ridia and tumors. We report in the present paper a preliminary in situ hybridization study of PA3-, PAX5- and PAX6-gene expression during hu man embryonic development. PAX3-gene is expressed in the neural groove before closure, and in the closed neural tube. Afterwards, its expres sion is observed in the mesencephalon, the rhombencephalon and the spi nal cord. PAX5-gene expression is restricted to the mesencephalon-rhom bencephalon boundary and the spinal cord. PAX6-gene is expressed early in the neural tube, just after its closure. Afterwards, its expressio n is observed in the forebrain, the rhombencephalon, the somites and t he spinal cord. These patterns of expression are observed early during human embryonic development and are specific in time and spare. This preliminary report shows the feasibility of in situ hybridization meth odology for studying the expression of developmental genes during the early stages of human embryogenesis. It opens the way to study the pat hogenesis of polymalformative syndroms and tumorigenesis.