anatomical and histological study of penis in persian squirrel (sciurus anomalus)

background: the persian squirrel (sciurus anomalus) is a member of the family sciuridae in the middle east and very little information is available about the anatomy of the different organs of this animal. objectives: in this study, histological and macro anatomical structures of penis were examined on 6 adult male persian squirrels. methods: each animal was sacrificed after anesthesia with ketamine and xylazine then dissected openwith the penis exposed from its root. the penises were first grossly examined, and then root, body and free part of peniswere studied, using histological technics and staining h&e;, tcm and verhoeff. results: grossly, the color of penis was bright pink andthemean length of that was 5.87 ± 0.68 cm. a caudo-ventral curvature separates the free part of the penis, i.e.the glans in the middle part and the nail in the head part, from the body part. histologically, the ducts cooper are branched after entering in penile bulb and make a large glandular structure in the bulb, then as a single duct continue along the body of penis with urethra and below it continue up to the free part. two corpora are confluent in the body and form a uniform and crescent of corpus cavernosum that surrounded by tunica albuginea and converted to os penis in the free part. therefore, from a histological standpoint, the persian squirrel penis belongs to the intermediatetype. conclusions: these findings provide vital information on the penile anatomy of the persian squirrel, which will serve as a basis for comparing penile morphology among thesuborder hystricomorpha and expand knowledge of the reproductive biology in this animal.