Abstract
The insemination reaction is a well known phenomenon in the Drosophila species after Patterson (1946), and plays a role on the post-mating isolating mechanisms. Fecundity was significantly reduced when the insemination reaction was occurred in interspecific crosses between D. nasuta and D. pallidifrons accompanied a formation of large reaction mass in the uterus, although the insemination reaction did not affect the oviposition in intraspecific crosses. The reaction mass was formed in uterus within 10min after copulation. In crosses with XO sterile males, the formation of reaction mass was observed as frequently as XY males.
Polyacrylamide gel electrophoresis and fluorography were used to clarify the chemical components of reaction masses. Reaction masses were composed of various kinds of proteins produced by the interaction of secretions from reproductive organs of both sexes.
