Comparative Anatomical Study of the Epidural Retia Mirabile in the Yak and Cattle

摘要

The epidural retia mirabile is an arterial network formed by many of anastomotic branches from adjacent arteries for supplying blood to the brain in artiodactyla and plays a vital role in regulating cerebral blood flow. The purpose of this work was to compare anatomical differences of the epidural retia mirabile between the yak and cattle and to analyse their blood supply characteristics and provide a morphological basis for further research on the plateau adaptability of the yak. The vascular casts of the epidural retia mirabile were yielded on head specimens of 12 yaks (obtained from Qinghai China) and 10 cattle (obtained in Gansu China) by the corrosion casting technique. Their morphological features and arterial diameters were compared and analyzed using the methods of comparative anatomy. The general arrangements of the epidural retia mirabile in the yak were similar to that seen in cattle and mainly composed of the anterior portion, posterior portion, basi-occipital arterial plexus and anterior V-shaped extension. Middle width of the anterior epidural retia mirabile was more extensive and the posterior joint section was more developed and there were more abundant anterior anastomotic branches and communicating rami in the epidural retia mirabile of the yak. Moreover, the distribution ratios of blood flow from the maxillary artery entering the anterior epidural retia mirabile were 33.12% and 30.42% in the yak and in cattle, respectively. Our results indicated that the yak has more developed epidural retia mirabile. Its anatomical peculiarity perhaps is an adaptive characteristic of supplying blood system to the brain and which would help to buffer and regulate cerebral blood flow better so as to meet the cerebral oxygen demand of the yak in plateau areas.