ELASMOBRANCH BRAIN ORGANIZATION 



149 



mlf niv 



2 mm 



nin 



Figure 20 Transverse sections through the mesencephalon and caudal diencephalon of 

 Raja eglanteria. Magnification of d is 0.2X greater than other sections, al, anterior lobe of 

 the cerebellum; bon, basal optic nucleus; cpn, central pretectal nucleus; cz, central tectal 

 zone; dt, dorsal thalamus; ew, Edinger-Westphal nucleus; gl, granular layer of cerebellar 

 cortex; il, inferior lobe of hypothalamus; in, interpeduncular nucleus; It, lateral tegmental 

 nucleus; ml, molecular layer of cerebellar cortex; mlf, medial longitudinal fasciculus; mln, 

 mesencephalic lateralis nucleus; mV, trigeminal mesencephalic nucleus; ni, nucleus isthmi; 

 nil, nucleus of the lateral lemniscus; nlll, oculomotor nucleus; nIV, trochlear nucleus; pc, 

 Purkinje cell layer of the cerebellar cortex; pi, pituitary gland; pz, periventricular or deep 

 tectal zone; sco, subcommissural organ; spn, superficial pretectal nucleus; sv, saccus 

 vasculosus; sz, superficial tectal zone; teg, midbrain tegmentum; vt, ventral thalamus; III, 

 oculomotor nerve. 



