Morphology and Evolutionary Biology of the Dolphin (Delphinus sp.) Brain – MR Imaging and Conventional Histology

摘要: Whole brains of the common dolphin (Delphinus delphis) were studied using magnetic resonance imaging (MRI) in parallel with conventional histology. One formalin-fixed brain was documented a Siemens Trio Magnetic Resonance scanner and compared to three other which embedded celloidin, sectioned main planes stained for cells fibers. The is large, telencephalic hemispheres dominating stem. neocortex voluminous cortical grey matter thin but extremely extended densely convoluted. There no olfactory ventricular recess due lack an anterior system (olfactory bulb peduncle). No occipital lobe hemisphere posterior horn lateral ventricle are present. A pineal organ could not be detected. stem thick underlies very large cerebellum. hippocampus mammillary body small fornix thin; contrast, amygdaloid complex cortex limbic extended. visual well developed exceeded by robust auditory system; example, inferior colliculus several times larger than superior colliculus. Other impressive structures brainstem peculiar elliptic nucleus, olive, cerebellum huge paraflocculus interpositus nucleus. good correspondence between MR scans histological sections. Most characteristics can interpreted as morphological correlates successful expansion this species marine environment, characterized development powerful sonar localization, communication, acousticomotor navigation.