Preservation of the morphological and molecular stability of embryonic tissues.

There is presently great interest in using early embryonic tissues, particularly human tissue, for studies of protein and gene expression. Embryonic human tissue is very fragile, and delays often occur before it can be properly prepared for scientific study. Using chick embryos, we have studied the effects of delaying fixation or biochemical isolation on the preservation of cytological characteristics and biochemical molecules. Our study shows that by 60 min post-harvest, tissue morphology and immunofluorescence staining degrades, but the total mRNA profile remains stable. This study suggests that the time between removal of the tissue and fixation is critical to the results and that the critical time is much shorter for embryonic tissues than for more developed tissues. Our results have implications for all research where embryonic tissues are harvested but not processed immediately.