Scanning electron microscopy of endolithic algae and fungi using a multipurpose casting-embedding technique

An embedding-casting method was developed to preserve endolithic algal and fungal structures in situ and to make them optically accessible by removal of carbonate matrix. A slow penetration of Epon-812 resin was applied to fill fine boring tunnels and to embed the organisms within the rock. Fixed, dehydrated, embedded organisms were protected from structural damage during the dissolution of the matrix. Remaining Epon-cast reflects boring patterns and surface details. Casts were studied by a scanning electron-microscope and interpreted by an incident light microscope. After being reembedded in Epon-812, the preparations were sectioned, thin-ground and mounted for study by regular light and electron microscopy.