Fig. 4. The survival of (A) fat body and (B) midgut tissue samples decreased when they were frozen in the presence of an aquaporin inhibitor, mercuric chloride. Controls (held at 4°C for 4 h) were incubated in Coast's solution + 0.25 mol l^–1 glycerol with or without 0.2 mmol l^–1 HgCl₂. The remaining groups, labelled Coast's, Coast's + glycerol (Coast's solution + 0.25 mol l^–1 glycerol), mercuric chloride (Coast's solution + 0.25 mol l^–1 glycerol + 0.2 mmol l^–1 HgCl₂) and β-mercaptoethanol (Coast's solution + 0.25 mol l^–1 glycerol + 0.2 mmol l^–1 HgCl₂ + 2 mmol l^–1 β-mercaptoethanol), were cooled from 4°C to –20°C over 2 h and held at –20°C for 2 h before cell viability was assessed (N=4 per treatment). Different letters signify a significant difference between mean cell survival among treatments (P<0.05).