Hexamethyldisilazane for scanning electron microscopy of gastrotricha

We evaluated treatment with hexamethyldisilazane (HMDS) as an alternative t o critical-point drying (CPD) for preparing microscopic Gastrotricha for sc anning electron microscopy (SEM). We prepared large marine (2 mm) and small freshwater (100 mu m) gastrotrichs using HMDS as the primary dehydration s olvent and compared the results to earlier investigations using CPD. The re sults of HMDS dehydration are similar to or better than CPD for resolution of two important taxonomic features: cuticular ornamentation and patterns o f ciliation. The body wall of both sculpted (Lepidodermella) and smooth (Do lichodasys) gastrotrichs retained excellent morphology as did the delicate sensory and locomotory cilia. The only unfavorable result of HMDS dehydrati on was an occasional coagulation of gold residue when the solvent had not f ully evaporated before sputter-coating. We consider HMDS an effective alter native for preparing of gastrotrichs for SEM because it saves time and expe nse compared to CPD.