Fig. 6.

Dissected brain of a dog with radiopaque contrast filled cerebral ventricles. The midsagittal dissection (Fig. 6) demonstrates that the midbrain colliculi, outlined by multiple small arrows, is relatively similar in size when compared with cat in Fig. 5. However, the neocortical occipital lobe and pole (OP) when compared to the cat in Fig. 5 appear to extend further posteriorly of the cerebellum. A small cleft, indicated by a small green arrow, likely indicates the separate superior and inferior colliculi of the quadrigeminal plate. The collicular ventricle (CV) with its superior extensions features and its continuity with the midbrain aqueduct (Aq) are demonstrated in both the dissected specimen and the lateral radiograph. Additional abbreviations: 3 V, 3^d ventricle; 4 V, 4^th ventricle. The distance between 2 black lines on the ruler in the specimen photograph is 1 mm