Gillis , GaryYu, WesleyBrennan, PatriciaLee, Autumn2024-07-022024-07-022024-07-02https://hdl.handle.net/10166/6739Until now, little was known about the morphological characteristics of the retractor penis magnus and its relationship with the hemipenis during copulation. Prior research describes only the basic function of pulling back in and retracting the everted hemipenis. However, more recent studies have observed morphological aspects of the retractor penis muscles suggesting a function beyond retraction. In addition, observations in the Brennan Lab of the muscle compared to the hemipenis have also suggested that size does not necessarily correlate between the two structures, raising further questions regarding the purpose and function of this structure during copulation. Through histological analysis, we gained a deeper understanding of the complex interplay between form and function of this structure, enabling us to draw more accurate conclusions about its function. In particular, there is evidence that this muscle provides rigidity to the hemipenis during copulation by its fiber arrangement. The findings from this study could offer broader implications for understanding sexual selection, reproductive strategies, and evolutionary patterns in snakes. Through this multidisciplinary approach, the study aims to enhance our understanding of the complex interplay between form and function in snake reproductive organs, offering valuable insights into the evolutionary biology of snakes and potentially other reptiles.en-USRetractor penis magnusHistologyCopulationHemipenisThesispublic