Sexual Dimorphism in Lori Sheep Vomeronasal Organ dimensions and their relationships with external body measurements

Abstract

This experiment was carried out to study the effect of gender on anatomy of vomeronasal organ (VNO) and their correlations with some external body measurements in Lori sheep. Six external body characteristics were measured on 21 Lori sheep (10 ewes and 11 rams). Heads of the animals were collected and several transverse sections were made through the rostral region of incisive tubercle and repeated at every 1.5 cm up to the point that macroscopic signs of the VNO disappeared. The mean length of VNO was not differ between males and females (p<0.05). The average width of VNO in the middle and rostral third parts, the mean height of the organ in the middle third part and the mean distance between left and right VNO cartilaginous capsule in the middle third part were significantly greater in males compared with females. The width of the tubercle on incisive was significantly greater in males than females (9.99 vs. 8.42 mm). Average width of VNO in rostral third was significantly correlated with trunk length (p>0.05). The mean height of VNO lumen in middle and rostral third was negatively correlated with chest height (r = -0.476) and testis circumference (r = -0.731), respectively (p>0.05). The average width of the distance between left and right VNO lumen in middle third segment was significantly correlated with external nose circumference (p>0.05). Width and length of the tubercle on incisive were both significantly related with trunk length, and the former showed also a significant positive association with heart girdle (p>0.05). In conclusion, minor macroscopically differences exist especially in the middle third segment of VNO in Lori ram and ewe. The VNO anatomical parameters show significant correlations with common external body measures which their physiological interpretation needs further  investigation.

Keywords: Vomeronasal organ, Hard palate, External body measures, Lori sheep