Sterile hybrids and fertile males transfer seminal products that
trigger morphological changes of the uterus
Interrupted copulations showed significant differences between males
from parental population and sterile male hybrids in proportion of
seminal fluid masses present at two minutes interruptions (parentals=
87.5%; sterile males= 33.3%; Fisher-Exact test P =
1.3x10-8) but by six minutes the differences were
non-significant (parentals= 97.7%; sterile males= 86.5%; Fisher-Exact
test P = 0.068) (Table 2). This result shows that sterile males
take longer, but effectively transfer seminal fluids. Moreover, the
transfer of seminal fluids triggers similar morphological responses in
the female reproductive tract of females mated to fertile or sterile
males. The uterus is compacted in virgin females, with the seminal
receptacle located ventrally (Figure 2A). By two minutes, the uterus
experiences partial elongation acquiring a more oval shape and the
seminal receptacle is displaced opposite to the gonopod (Figure 2B). At
this point, the seminal fluid and possibly sperm (the ejaculate) can be
sometimes detected as a darker mass inside the uterus (Figure 2B). By
six minutes the uterus is fully elongated, with an oval shape, and both
the ejaculate mass and the ejaculate plug are visible (Figure 2C). In
females mated to sterile males, besides taking longer for the seminal
fluid mass to be transferred (Table 2), a major noticeable difference is
the lack of sperm within the seminal fluid mass transferred by sterile
males into the uterus (Table 2) (Figures 2 D and 2E).