title: Anatomical and histological equivalence of the human, canine, and bull vas deferens.
abstract: BACKGROUND
  Several animal models have been utilized for in-vitro experimentation and surgical training exercises of the vas deferens. The canine model is currently the standard for both in-vivo and ex-vivo study. Due to increasing costs associated with experimentation on canines, and in keeping with the principles of refine, reduce, and replace, a novel model that is cost-effective and easily obtained is desired. We compared morphology of the bull vas deferens to that of the human and the canine.
  
  
  METHODS
  Bilateral vas deferens tissue from the human (n = 6), canine (n = 6), and bull (n = 5) were compared. Outer diameter (OD), inner diameter (ID), and microscopic measurements of the luminal mucosa and muscularis were then determined from each of these tissues. Histological comparisons were performed by a single pathologist. Data was analyzed using Two One-sided Tests (TOST) Analysis of Equivalence.
  
  
  RESULTS
  According to the TOST statistical analysis, the vassal ID was equivalent for all three species. Similarly, equivalent microscopic measurements were noted for both vassal mucosal (human-canine and human-bull) and muscularis thicknesses (canine-bull). Lastly, all three species had similar histological characteristics.
  
  
  CONCLUSIONS
  The vas deferens' of the human, canine, and bull are equivalent in many ways, including histological similarities. It is reasonable to conclude that the bull vas could be substituted for the human vas for both in-vitro testing and microscopic vasovasostomy simulation exercises. Specimens are cost-effective, provide ample tissue length, and are easy to obtain.
authors.affiliation: Department of Urology, State University of New York at Upstate, Syracuse, 13210, USA.
authors.forename: Dean E
authors.initials: DE
authors.lastname: Leocadio
authors.forename: Allen R
authors.initials: AR
authors.lastname: Kunselman
authors.forename: Timothy
authors.initials: T
authors.lastname: Cooper
authors.forename: Jairo H
authors.initials: JH
authors.lastname: Barrantes
authors.forename: J C
authors.initials: JC
authors.lastname: Trussell
mesh_terms: D000818:Animals; D002417:Cattle; D003362:Cost-Benefit Analysis; D004285:Dogs; D006801:Humans; D008297:Male; D023421:Models, Animal; D013045:Species Specificity; D013521:Urologic Surgical Procedures, Male / Q000191:economics / Q000193:education; D014649:Vas Deferens / Q000033:anatomy & histology* / Q000166:cytology* / Q000601:surgery; D014669:Vasovasostomy / Q000191:economics / Q000193:education