Laser-mediated microdissection of paraffin sections from Xenopus embryos allows detection of tissue-specific expressed mRNAs

One of the key end points for understanding the molecular basis of embryoge nesis is the analysis of spatiotemporal patterns of gene expression. Method ical limitations due to low mRNA levels often prevent a tissue-specific res olution. In this study, we developed an improved laser microdissection tech nique and RT PCR that allows marker gene detection in small tissue areas fr om sections of formalin-fixed paraffin-embedded Xenopus embryos. Tissue pie ces were isolated by laser microbeam microdissection and captured by laser pressure catapulting. Neither laser treatment nor conventional histological or immunochemical staining impaired subsequent RNA analysis. Transcripts o f tissue-specific marker genes such as endodermin (endoderm), epidermal cyt okeratin (epidermal ectoderm), N-CAM (neural tube), myoD (somites), and son ic hedgehog (floor plate) were amplified by nested RT PCR analysis from sma ll areas of single sections.