ANATOMICAL COMPARTMENTS IN THE WHITE-MATTER OF THE RABBIT FLOCCULUS

The white matter of the rabbit flocculus is subdivided into five compa rtments by narrow sheets of densely staining acetylcholinesterase-posi tive fibers. The most lateral compartment is continuous with the C-2 c ompartment of the paraflocculus and contains the posterior interposed nucleus. The other four compartments are numbered from lateral to medi al as floccular compartments 1, 2, 3, and 4 (FC1-4) FC1-3 continue acr oss the posterolateral fissure into the adjacent folium (folium p) of the ventral paraflocculus. FC4 is present only in the rostral flocculu s. In the caudal flocculus FC1 and FC3 abut dorsal to FC2. Fibers of F C1-4 can be traced into the lateral cerebellar nucleus and the floccul ar peduncle. The presence of acetylcholinesterase in the deep stratum of the molecular layer of the flocculus and ventral paraflocculus dist inguishes them from the dorsal paraflocculus. The topographical relati ons to the flocculus and the floccular peduncle with group y and the c erebellar nuclei are discussed. (C) 1995 Wiley-Liss, Inc.