HIST - Preparing Specimens Without Critical Point Drying

Created by Karen Darley, Modified on Wed, 11 Dec at 2:47 PM by Kathleen Patrick

For fast preparation of soft insect tissues, also bacteria and some other "hardy" specimens in lieu of CPD.

Required

Hexamethyldisilazane (HDMS)

Hepes buffer

Method

After glutaraldehyde fixation, washing and dehydration through a graded series of ethanol, like: 70%, 85%, 95% and 100%, 5 min in each. Then specimens are immersed in HDMS for 5 min, air dried at room temperature and mounted on stainless steel stubs with double sticky tabs. This treatment gives results as good as those from critical point drying. Its chief advantage lies in the speed with which small pieces of tissue can be prepared for gold coating, compared with the critical point drying technique (about 5 min vs 1.5 h).

In addition, the method is inexpensive and does not require special equipment or skills. Slower drying may further reduce shrinkage. Place two filter papers into a glass Petri dish then add a microscope slide. Saturate the paper with HDMS and then place HMDS treated specimens onto the glass slide. Cover with lid and leave to dry overnight.

Reference: Nation, J.L. - Stain Technology 58 (6), 347-350 (1983).