Anatomical classifications of accessory symphyseal foramina in infants, juveniles and adults raccoon (Procyonoides nyctereutes) mandibles

Abstract

The aim of this investigation was to assess the pattern of occurrence of accessory foramina in infants, juveniles and adult raccoons (Procyonoides nyctereutes). The study utilized a total of forty (40) mandibles including thirteen (13) infantile (pups), twelve (12) juveniles and fifteen (15) adult mandibles , studied grossly for frequency, position and diameter of the foramina. In 80% of the evaluated adult mandibles, at least one accessory foramen was found and superolaterally located. In all juveniles (100%) at least one accessory foramen was present, and located mostly near the midline about half - way of the symphyseal length while in pups (94%) at least a foramen was present, and in all cases located at or near the sympyseal line (rostral third or caudal third) to the dorsal ridge but never central. Five distinct co-existence types were used in their classification into foramina as categories I a-d, II a-c, III, IV and V. The frequency, size and location varied between the age groups; category 1 types occurred in 33%, 33% and 30% of adults, juveniles and pups respectively, category II in 33%, 42% and 54%; category III, 3.8%, 2.2% and 5.8%; category IV,1.9%, 4.4% and  11.7%; category V, 3.8%, 2.2% and 0%; respectively. Accessory symphyseal foramina are structural occurrences in raccoon mandible with size, frequency and position variations depending on classification type. There were no significant variations in the accessory symphyseal foramina assessed within pups. This work gives base line information on the phenotypes of accessory mental foramen in post natal development in the raccoons.

Keywords: Raccoons, Mandibles, Accessory foramina, Symphyseal ridge