VENTRICULAR SYSTEM OF BRAIN OF DOLPHIN TURSIOPS TRUNCATUS WITH COMPARATIVE ANATOMICAL OBSERVATIONS AND RELATIONS TO BRAIN SPECIALIZATIONS

A comparative and quantitative anatomical study of the cerebral ventricular system of the dolphin, Tursiops truncatus, and six other mammalian species, including man, has been made in the course of extensive neuroanatomical investigations of the dolphin. Several techniques have been used in these studies to confirm the morphological arrangement and contours of the ventricles. Casts of the ventricles were produced by use of a variety of casting media and methods and their relative merits were investigated and described. Following injection of the brain with casting media, the brain was either totally removed by dissection or digestion or one hemisphere dissected away to reveal the relationships of the ventricular cast to the opposite cerebral hemisphere. Serial sections of the brains of three dolphins were cut in three cardinal planes, and from these a model of the entire ventricular system was reconstructed. Serial sections (Nissl and Loyez) were also used to identify structures closely related to the ventricular cavities. Our results show that components of the cerebral ventricular system of the dolphin reflect, to a considerable degree, many of the specialized features of that brain including brachycephaly, widened and foreshortened temporal lobes, large limbic lobe, hypodeveloped frontal region, absence of an occipital pole, and massive development of the tectal acoustic apparatus. The morphological characteristics of the ventricular system and the relationship of this system to brain areas is discussed with respect to possible functional and phylogenetic implications. Copyright © 1969 The Wistar Institute of Anatomy and Biology