Carbowax for Embedding and Serial Sectioning of Botanical Material

Plant material infiltrated with gradually increasing concentrations of Carbowax 400, followed by Carbowax 1540 and finally a 19:1 embedding mixture of Carbowax 1540 and 4000 showed minimum shrinkage. Quantitative measurements of shrinkage in tissue of potato tubers gave the following amounts: fixation and washing, about 4%; transfer from water directly to 70% Carbowax 400, 5176; from water through a graded series (5, 10, 15, 20, 30, 40, 50 and 60% Carbowax) to 70%, only 2.5% shrinkage; with an additional 1.5% occurring in transition to the embedding mixture. Dry ribbons are placed on adhesive-coated (gelatin, 5 gm; water, 120 ml; glycerol, 40 ml; phenol, 2 gm) slides in a humidity chamber. In 10-15 min enough moisture is absorbed by the ribbon to float the sections out gently and bring them in contact with the adhesive. Slides are then dried 5-10 min at room temperature. To remove minor wrinkles, the sections are subsequently flooded with water, then redried 12-24 hr; after which, they are ready for staining.