First evidence of hemiclitores in snakes

Female genitalia are conspicuously overlooked in comparison to their male counterparts, limiting our understanding of sexual reproduction across vertebrate lineages. This study is the first complete description of the clitoris (hemiclitores) in female snakes. We describe morphological variation in size and shape (n = 9 species, 4 families) that is potentially comparable to the male intromittent organs in squamate reptiles (hemipenes). Dissection, DiceCT and histology revealed that, unlike lizard hemiclitores, the snake hemiclitores are non-eversible structures. The two individual hemiclitores are separated medially by connective tissue, forming a triangular structure that extends posteriorly. Histology of the hemiclitores in Australian death adder (Acanthophis antarcticus) showed erectile tissue and strands/bundles of nerves, but no spines (as is found in male hemipenes). These histological features suggest the snake hemiclitores have functional significance in mating and definitively s..., Specimens and euthanasia
We examined female genitalia in ten adult specimens, eight frozen, and two fresh-fixed females, across nine species: Acanthophis antarcticus, Agkistrodon bilineatus, Bitis arietans, Helicops polylepis, Lampropeltis abnorma, Morelia spilota, Pseudechis colleti, Pseudechis weigeli, and Pseudonaja ingrami. We also examined the micro-anatomy of the male genitalia in an adult and a juvenile specimen (Acanthophis antarcticus) (Table S1). The adults were wild caught and were sourced from either Venom Supplies Pty. Ltd., private collections, or the University of Michigan Museum of Zoology (UMMZ). The juvenile A. antarcticus was born at Venom Supplies.
Once euthanised via injection of pentobarbitone, the specimens were immediately frozen at -20°C. Adult female, male, and juvenile male A. antarcticus specimens were used for histology, and an adult female was used for diffusible iodine contrast-enhanced µCT (DiceCT) scanning (Table S1). The adult females of A. bilineatus, ..., Histology - Images, no programs needed. CZI data available on request - would use ZEN 3.4 (blue eddition)
DiceCT - Avizo or DragonflyÂ