Binding and uptake of trypan blue by developing oocytes of Locusta migratoria migratorioides

Resorbing oocytes are heavily stained by trypan blue injected into the haemolymph; this serves as a basis for a quick and convenient method for measuring the degree of resorption. Oocytes in the beginning of their development are most susceptible towards resorptive tendencies. The uptake of trypan blue by normally developing oocytes is proportional to the oocyte surface. From 'double-marker' experiments, in which trypan blue is injected into the haemolymph together with [3H]inulin (which does not bind to the oocyte membrane) it is estimated that the contribution of binding in the interiorization of trypan blue is in the order of 80%, under the conditions given. In vitro incubations show the interaction of trypan blue with the membrane to be electrostatic in nature.