Among insect species, the male genitalia evolved many different anatomical features to ensure reproductive success. Males of primitive insects do not copulate but transfer sperm packaged in a spermatophore to the female, whereas males of the most advanced insects copulate and deliver free sperm to the storage organ, the spermatheca, in the female reproductive tract. Based on previous studies on several species of triatomine bugs (Rhodnius prolixus included), Triatominae are thought to use an intermediate form of sperm transfer in which the male genitalia have evolved to carry out both copulation and spermatophore formation. Previous observations on chemically fixed tissue of R. prolixus appear to show that the penis, the aedeagus, contains a much-folded internal cuticle which is a collapsed sac that everts from the aedeagus during copulation for the formation and delivery of the spermatophore directly to the female genital chamber. However, observations on living tissue of these structures in R. prolixus show that this internal cuticle functions as a tube through which male secretions pass through the aedeagus to the vagina. The organization of this cuticle in the context of the various anatomical structures of the aedeagus, its different morpho-functional meaning during sperm transfer in R. prolixus, the use of living versus chemically fixed tissue and a new understanding of previous observations are discussed.

在昆虫种类中，雄性生殖器进化出许多不同的解剖特征以确保繁殖成功。原始昆虫的雄性不交配，而是将精子包装的精子转移给雌性，而最高级昆虫的雄性交配，并将游离的精子传递到雌性生殖道的储存器官，即精子中。根据先前对几种三角藻类小虫（包括Rhodnius prolixus）的研究，认为三角藻科使用的是精子转移的一种中间形式，其中雄性生殖器已经进化为既可进行交配又可形成精子。关于螺旋藻化学固定组织的先前观察似乎表明，阴茎，即阴茎，包含一个折叠得很厉害的内角质层，它是一个塌陷的囊，在交配过程中会从阴茎中浮出，以将精子直接形成并输送到女性生殖器腔。然而，对Pro.prolixus中这些结构的活组织的观察表明，该内部表皮起着管的作用，雄性分泌物通过该管穿过七叶科进入阴道。讨论了该表皮的组织结构，包括七叶树的各种解剖结构，在R. prolixus精子转移过程中其不同的形态功能含义，对活体和化学固定组织的使用以及对先前观察结果的新理解。