Interpreting morphological adaptations associated with viviparity in the Tsetse fly (Glossina morsitans) by three-dimensional analysis

Tsetse flies (genus Glossina), the sole vectors of African
trypanosomiasis, are distinct from other disease vectors, and most other
insects, due to dramatic evolutionary adaptations required to support
their unique life history. These morphological and physiological
adaptations are driven by demands associated with their strict dietary and
reproductive requirements. Tsetse reproduce by obligate viviparity which
entails obligate intrauterine larval development and provisioning of
nutrients for the developing larvae. Viviparous reproduction reduces
reproductive capacity/rate which also drives increased inter- and
intra-sexual competition. This work describes three-dimensional (3D)
analysis of viviparity associated morphological adaptations of tsetse
female reproductive tract as well as that of male seminal secretions by
phase contrast microcomputed tomography (pcMicroCT). Structural features
of note include abdominal modifications facilitating the extreme abdominal
distention required during blood feeding and pregnancy; abdominal and
uterine musculature required for parturition of developed larvae;
reduction of ovarian structure and capacity; structural features of the
male seminal spermatophore that enhance sperm delivery and inhibition of
insemination by competing males; uterine morphological features
facilitating expansion and contraction before, during and after pregnancy;
analysis of structural optimizations of the milk gland facilitating
nutrient incorporation and transfer into the uterus. The use of pcMicroCT
provides unprecedented opportunities for examination and discovery of
internal morphological features not possible with traditional microscopy
techniques and new opportunities for comparative morphological analyses
over time and between species.